Tiny whoop case with drop-in whoop and charger trays, port dial and LAVA battery clips

// Tiny whoop case with drop-in trays: the same hinged case for every setup, a whoop
// tray with a pocket per whoop model, and a charger tray that fits any BetaFPV
// charger with two bolted jaws and walls that lean over it. A dial in the front wall
// opens the window to the charging port. The lid holds LAVA 1S batteries standing
// on their side. Printed in PETG, every part without supports.
//
// Coordinates: y = 0 at the rear (hinges), y = Sy at the front (latch). Seen from
// the front with the lid open behind, the viewer's right is low x: the charger tray
// sits there, the whoop tray beside it. The lid is modelled closed and flipped for
// printing.

/* [Part] */
// The whole case with the lid open, or one part in print orientation.
part = "assembly"; // [assembly, base, lid, whoop_tray, charger_tray, jaws, port_dial]
// Print a coupon set instead: one hinge and the latch in base and lid halves, the
// dial in its piece of wall, a jaw with a piece of its channel, one whoop catch and
// one battery clip.
test_print = false;
// Show the whoop, the charger and the batteries as ghosts in the assembly.
show_contents = false;

/* [Whoop] */
// The whoop the tray pocket is shaped for.
whoop = "Meteor75 Pro II"; // [Meteor75 Pro II, Meteor75 Pro, Air75 or Meteor75, Meteor65 Pro II, custom]
// For custom: motor to motor across the diagonal, outer diameter of one duct, and
// height of the duct rim above the bottom of the whoop.
custom_wheelbase = 75; // [50:0.5:81]
custom_duct_d = 48; // [30:0.5:53]
custom_frame_h = 16; // [10:0.5:16.5]
// Total height of the whoop with its camera; sets the case height.
whoop_h = 40; // [25:1:60]

/* [Charger] */
// The charger the window lines up with. The charger tray itself fits all of them.
charger = "BetaFPV 6-port"; // [BetaFPV 6-port, BetaFPV 2-port V2, custom]
// For custom: port centre from the outer side of the charger, and above its bottom.
custom_port_x = 20; // [8:0.5:40]
custom_port_z = 9; // [4:0.5:16]

/* [Batteries] */
// LAVA II size family: 480, 580 and 680 are 15.5 mm tall as they stand, 280 and
// 320 are 10 mm.
battery = "LAVA II 480 580 680"; // [LAVA II 480 580 680, LAVA II 280 320]
battery_count = 8; // [0:1:12]

/* [Colour] */
// Display only, the STL carries no colour.
color_case = "SteelBlue"; // [SteelBlue, White, DimGray, Black, FireBrick, Goldenrod, ForestGreen, MediumPurple]

/* [Hidden] */
$fn = 48;
wall = 3.2;
floor_t = 2;
top_t = 2;
corner_r = 6;
bot_ch = 1.5;
top_ch = 2;
seam_ch = 0.6;
// lip on the base rim, recess in the lid
lip_h = 2;
lip_t = 1.2;
lip_c = 0.25;
// clearance between a tray and the case
t_clr = 0.3;
// whoop tray: pocket floor, clearance round the whoop, room for the braces between
// ducts, catch bump and width, largest whoop footprint, tray size and height
w_floor = 1.2;
c_clr = 0.5;
brace = 5;
nub = 1;
nub_w = 8;
max_span = 110;
wt_w = max_span + 2 * c_clr + 2.4;
wt_h = w_floor + 16.5 + 2.6;
// charger tray: floor with the channels, wall height and top thickness, lean,
// rims, largest charger width, jaw plate and tab
ct_floor = 5.4;
ct_wh = 22;
ct_wt = 2;
lean = 10;
rim_h = 8;
rim_t = 1.6;
max_cw = 46;
jw_t = 3;
jw_w = 20;
jw_tab = 9;
tl = tan(lean);
ct_w = ct_wt + max_cw + jw_t + ct_wh * tl + 1 + rim_t;
ct_h = ct_floor + ct_wh;
// T channel: bolt slot, nut cavity width and height
ch_slot = 3.6;
ch_nut = 6.2;
ch_nut_h = 2.8;
// M3 hardware and the floor bosses the trays bolt to
bolt_d = 3.4;
nut_af = 5.7;
nut_ac = nut_af / cos(30);
nut_h = 2.6;
bs = 9;
boss_h = 5.7;
// port dial: diameter, thickness, offset of its opening from the pivot
dial_d = 39;
dial_t = 2;
dial_rw = 10;
// battery clips
bat_clr = 0.2;
arm_t = 1.4;
arm_w = 6;
arm_gap = 1.6;
bump = 0.7;
// hinges: knuckle radius, axis behind the rear face, segment width and gap
rk = 4;
hk = rk + 0.5;
seg_w = 8;
seg_gap = 0.4;
hinge_in = 22;
// latch
latch_w = 20;
latch_drop = 10;
tongue_t = 1.6;

// whoop presets: wheelbase, duct outer diameter, rim height
sel_w = whoop == "Meteor75 Pro II" ? [80, 52, 16.2]
  : whoop == "Meteor75 Pro" ? [80.8, 52, 16.5]
  : whoop == "Air75 or Meteor75" ? [75, 47.5, 16.5]
  : whoop == "Meteor65 Pro II" ? [70, 42, 15.4]
  : [custom_wheelbase, custom_duct_d, custom_frame_h];
wb = sel_w[0];
dd = sel_w[1];
fh = sel_w[2];
sq_s = wb / sqrt(2);
r_n = wb / 2 + dd / 2 + c_clr;
// charger presets: length, width, height, port from the outer side, port height
sel_c = charger == "BetaFPV 2-port V2" ? [52.7, 23.2, 14.2, 11.6, 7.1]
  : charger == "custom" ? [79, 46, 19, custom_port_x, custom_port_z]
  : [79, 46, 19, 23, 9.5];
cl = sel_c[0];
cw = sel_c[1];
chh = sel_c[2];
// battery family: longest length, height as it stands, thickness
bat = battery == "LAVA II 280 320" ? [64, 10, 6] : [80, 15.5, 7];
battery_l = bat[0];
battery_w = bat[1];
battery_t = bat[2];
bat_pitch = battery_t + 2 * (bat_clr + arm_t) + arm_gap;

Sx_in = ct_w + wt_w + 3 * t_clr;
D = max(wt_w, battery_l + 12);
Sy_in = D + 2 * t_clr;
Sx = Sx_in + 2 * wall;
Sy = Sy_in + 2 * wall;
fz = floor_t;
cav_h = max(w_floor + whoop_h + 2, ct_h + 1, wt_h + 1);
base_h = fz + cav_h;
zc = base_h;
lid_cav = max(battery_w + 2.5, 9);
lid_h = top_t + lid_cav;
pb = zc + lid_h - top_t;
yf = Sy - wall;
// trays
ct_x0 = wall + t_clr;
ct_y0 = wall + t_clr;
wt_x0 = ct_x0 + ct_w + t_clr;
wt_y0 = ct_y0;
wcx = wt_x0 + wt_w / 2;
wcy = wt_y0 + D / 2;
// the charger in its tray, tray coordinates: it touches the leaning walls with its
// top edges
x_o = ct_wt + chh * tl;
y_fc = D - ct_wt - chh * tl;
// window and dial: the opening sits a quarter turn of offset below and outboard of
// the pivot, kept clear of the corner and the bottom chamfer
da = dial_rw / sqrt(2);
px = max(ct_x0 + x_o + sel_c[3], corner_r + 0.5 + dial_d / 2 + 0.2 - da);
pz = max(fz + ct_floor + sel_c[4], bot_ch + 0.5 + dial_d / 2 + 0.2 - da);
pvx = px + da;
pvz = pz + da;
win = [[-7, -4.5], [7, -4.5], [7, 1.5], [4, 4.5], [-4, 4.5], [-7, 1.5]];
// tray bolts
wb_x = wcx;
wb_y = wcy - 45;
cb_x = ct_x0 + 12;
cb_y = ct_y0 + 9;

// ---- 2D helpers ----

module outer2d() {
  offset(r = corner_r) offset(delta = -corner_r) square([Sx, Sy]);
}

module inset2d(k) {
  offset(r = -k) outer2d();
}

module ring2d(a, b) {
  difference() { inset2d(a); inset2d(b); }
}

// Horizontal hole that prints without support: the tip points up in 2D y.
module teardrop2d(r) {
  circle(r = r);
  rotate(45) square(r);
}

// Whoop outline: four ducts on a square of side s, and the frame between them.
module whoop2d(s, d) {
  for (sx = [-1, 1], sy = [-1, 1]) translate([sx * s / 2, sy * s / 2]) circle(d = d);
  square(s, center = true);
}

// ---- Hinge ----
// Knuckle profile in (y, z) about the hinge axis, which sits hk behind the rear face
// at rim height. Its underside runs into the wall at 45 degrees. The lid mirrors it
// about the rim, so both halves print without support.

module knuckle_profile() {
  difference() {
    hull() {
      translate([-hk, 0]) circle(r = rk);
      translate([-0.01, -hk - 1.42 * rk]) square([1, hk + 1.42 * rk - 2]);
    }
    translate([-hk, 0]) teardrop2d(bolt_d / 2);
  }
}

module knuckle2d(upper) {
  translate([0, zc]) {
    if (upper) mirror([0, 1]) knuckle_profile();
    else knuckle_profile();
  }
}

// Two hinges, each base-lid-base on one M3 x 30 bolt with a nut.
module knuckles(upper) {
  for (gx = [hinge_in, Sx - hinge_in], k = upper ? [0] : [-1, 1])
    translate([gx + k * (seg_w + seg_gap) - seg_w / 2, 0, 0])
      rotate([90, 0, 90]) linear_extrude(seg_w) knuckle2d(upper);
}

// ---- Base ----

module base_shell() {
  difference() {
    union() {
      hull() {
        linear_extrude(0.01) inset2d(bot_ch);
        translate([0, 0, bot_ch]) linear_extrude(base_h - bot_ch - seam_ch) outer2d();
        translate([0, 0, base_h - 0.01]) linear_extrude(0.01) inset2d(seam_ch);
      }
      // lip on the inner half of the rim, it locates the lid
      translate([0, 0, base_h - 0.01]) linear_extrude(lip_h + 0.01) ring2d(wall - lip_t, wall);
    }
    translate([0, 0, floor_t]) linear_extrude(base_h + lip_h) inset2d(wall);
  }
}

// Boss on the floor under a tray: an M3 nut slides into a slot open toward +x, under
// 1.2 mm of material, and the tray bolts down into it from above.
module boss_at(x, y) {
  translate([x, y, 0]) difference() {
    translate([-bs / 2, -bs / 2, fz - 0.01]) cube([bs, bs, boss_h + 0.01]);
    translate([0, 0, fz - 0.5]) cylinder(d = bolt_d, h = boss_h + 1);
    translate([-nut_ac / 2, -nut_af / 2, fz + boss_h - 1.2 - nut_h]) cube([bs / 2 + nut_ac / 2 + 0.1, nut_af, nut_h]);
  }
}

// Window to the charging port. The top corners are chamfered at 45 degrees, so the
// top is an 8 mm bridge.
module port_window(depth) {
  translate([0, Sy + 1, 0]) rotate([90, 0, 0]) linear_extrude(depth + 1)
    translate([px, pz]) polygon(win);
}

// Round recess the dial sits flush in, and the hole for its pivot bolt.
module dial_recess() {
  translate([pvx, Sy + 1, pvz]) rotate([90, 0, 0]) {
    cylinder(d = dial_d + 0.4, h = dial_t + 1, $fn = 96);
    cylinder(d = bolt_d, h = wall + 2);
  }
}

// Boss inside the front wall behind the latch pocket, with a 45 degree underside.
module latch_boss() {
  hull() {
    translate([Sx / 2 - 14, yf - 3, zc - latch_drop - 3]) cube([28, 3.01, latch_drop + 3]);
    translate([Sx / 2 - 14, yf - 0.01, zc - latch_drop - 6]) cube([28, 0.02, 0.01]);
  }
}

// Recess for the flush tongue, a 45 degree lead-in over the wall top, the pocket the
// hook catches in, a scoop for a fingernail under the tongue, and a notch in the
// rim lip where the tongue passes.
module latch_cut() {
  zt = zc - latch_drop;
  translate([Sx / 2 - latch_w / 2 - 0.5, 0, 0]) rotate([90, 0, 90]) linear_extrude(latch_w + 1) {
    translate([Sy - 1.9, zt - 0.5]) square([3, latch_drop + 2]);
    polygon([[Sy - 1.89, zc - 1], [Sy - 1.89, zc + 1], [Sy - 2.9, zc + 1], [Sy - 2.9, zc]]);
    polygon([[Sy - 1.89, zt - 0.2], [Sy - 2.9, zt + 0.81], [Sy - 2.9, zt + 1.59], [Sy - 1.89, zt + 2.6]]);
    polygon([[Sy - 1.9, zt - 0.49], [Sy + 1, zt - 0.49], [Sy + 1, zt - 3.4]]);
  }
  translate([Sx / 2 - latch_w / 2 - 0.6, Sy - wall - 0.2, zc - 0.01]) cube([latch_w + 1.2, wall + 1.2, lip_h + 1]);
}

module base() {
  difference() {
    union() {
      base_shell();
      knuckles(false);
      latch_boss();
      boss_at(wb_x, wb_y);
      boss_at(cb_x, cb_y);
    }
    port_window(wall + 1);
    dial_recess();
    latch_cut();
  }
}

// Counterbored M3 hole through a tray, and the recess underneath for the floor boss.
module tray_bolt(x, y, ztop) {
  translate([x, y, 0]) {
    translate([0, 0, ztop - 3.5]) cylinder(d = 6.5, h = 4);
    translate([0, 0, fz - 1]) cylinder(d = bolt_d, h = ztop - fz + 2);
    translate([-5.2, -5.2, fz - 0.01]) cube([10.4, 10.4, boss_h + 0.3]);
  }
}

// ---- Whoop tray ----
// A block with a pocket shaped round the whoop, with room for the braces between
// neighbouring ducts. Four catches with 45 degree faces stand 1 mm out of the pocket
// wall just above the duct rims, at the outer point of each duct; the whoop clicks
// in under them.

module pocket2d() {
  offset(r = c_clr) {
    whoop2d(sq_s, dd);
    for (a = [0, 90, 180, 270]) rotate(a) translate([-10, sq_s / 2 - 1]) square([20, brace + 1]);
  }
}

module whoop_tray() {
  zn = fz + w_floor + fh + 0.2;
  difference() {
    translate([wt_x0, wt_y0, fz]) linear_extrude(wt_h) offset(r = 2) offset(delta = -2) square([wt_w, D]);
    translate([wcx, wcy, fz + w_floor]) linear_extrude(wt_h) pocket2d();
    tray_bolt(wb_x, wb_y, fz + wt_h);
  }
  for (sx = [-1, 1], sy = [-1, 1])
    translate([wcx + sx * r_n / sqrt(2), wcy + sy * r_n / sqrt(2), 0]) rotate(atan2(-sy, -sx))
      translate([0, nub_w / 2, 0]) rotate([90, 0, 0]) linear_extrude(nub_w)
        polygon([[-0.8, zn], [0, zn], [nub, zn + nub], [nub, zn + nub + 0.3], [0, zn + 2 * nub + 0.3], [-0.8, zn + 2 * nub + 0.3]]);
}

// ---- Charger tray ----
// A floor with two T channels, a front wall and an outer wall that lean over the
// pocket by lean degrees, low rims at the rear and the inner side, and a block at
// the rear corner for the bolt. Two jaws slide on the channels and push the charger
// into the front outer corner; every face it meets leans over it, so a charger of
// any height up to ct_wh is wedged in by its top edges.

// T channel in the tray floor from a to b, tray coordinates: a slot right through
// for the bolt, and a cavity for an M3 nut that cannot turn in it.
module t_channel(a, b) {
  hull() for (p = [a, b]) translate([p[0], p[1], -1]) cylinder(d = ch_slot, h = ct_floor + 2);
  hull() for (p = [a, b]) translate([p[0] - ch_nut / 2, p[1] - ch_nut / 2, 1]) cube([ch_nut, ch_nut, ch_nut_h]);
}

module charger_tray() {
  hb = ct_wh * tl;
  difference() {
    translate([ct_x0, ct_y0, fz]) union() {
      cube([ct_w, D, ct_floor]);
      rotate([90, 0, 90]) linear_extrude(ct_w)
        polygon([[D, ct_floor - 0.01], [D - ct_wt, ct_floor - 0.01], [D - ct_wt - hb, ct_h], [D, ct_h]]);
      translate([0, D, 0]) rotate([90, 0, 0]) linear_extrude(D)
        polygon([[0, ct_floor - 0.01], [ct_wt, ct_floor - 0.01], [ct_wt + hb, ct_h], [0, ct_h]]);
      cube([ct_w, rim_t, ct_floor + rim_h]);
      translate([ct_w - rim_t, 0, 0]) cube([rim_t, D, ct_floor + rim_h]);
      cube([24, 18, ct_floor + 8]);
    }
    translate([ct_x0, ct_y0, fz]) {
      t_channel([30.5, -4], [30.5, 56]);
      t_channel([27, D - ct_wt - 25.5], [ct_w + 4, D - ct_wt - 25.5]);
    }
    port_window(wall + t_clr + 12);
    // hex pocket for the nut of the dial bolt, a point up so it prints clean
    translate([pvx, ct_y0 + D + 0.01, pvz]) rotate([90, 0, 0]) {
      rotate([0, 0, 90]) cylinder(d = nut_ac + 0.3, h = nut_h + 0.3, $fn = 6);
      cylinder(d = bolt_d, h = 7);
    }
    tray_bolt(cb_x, cb_y, fz + ct_floor + 8);
  }
}

// ---- Jaw ----
// A plate leaning lean degrees toward the charger with a tab on its side for the
// bolt. Local frame: d toward the charger (the face top at d = 0), w along the jaw,
// z up from the tray floor. Prints upright.

module jaw() {
  hb = ct_wh * tl;
  difference() {
    union() {
      translate([0, jw_w / 2, 0]) rotate([90, 0, 0]) linear_extrude(jw_w)
        polygon([[-hb, 0], [0, ct_wh], [-jw_t, ct_wh], [-jw_t - hb, 0]]);
      translate([-jw_t - hb, jw_w / 2 - 0.01, 0]) cube([jw_t, jw_tab + 0.01, 3]);
    }
    translate([-jw_t / 2 - hb, jw_w / 2 + jw_tab / 2, -1]) cylinder(d = bolt_d, h = 5);
  }
}

// The jaws placed against the chosen charger: the rear one pushes it forward, the
// inner one pushes it outward. Each face touches the charger at its top edge.
module jaws_placed() {
  y0r = (y_fc - cl) + (ct_wh - chh) * tl;
  x0i = (x_o + cw) - (ct_wh - chh) * tl;
  multmatrix([[0, 1, 0, ct_x0 + 16], [1, 0, 0, ct_y0 + y0r], [0, 0, 1, fz + ct_floor], [0, 0, 0, 1]]) jaw();
  multmatrix([[-1, 0, 0, ct_x0 + x0i], [0, 1, 0, ct_y0 + D - ct_wt - 40], [0, 0, 1, fz + ct_floor], [0, 0, 0, 1]]) jaw();
}

module jaws_flat() {
  hb = ct_wh * tl;
  for (k = [0, 1]) translate([jw_t + hb + 2, k * (jw_w + jw_tab + 4) + jw_w / 2, 0]) jaw();
}

// ---- Port dial ----
// A disc flush in the front wall, turning on a countersunk M3 x 8 into the nut in the
// charger tray. Its opening sits dial_rw off the pivot, so half a turn opens or
// closes the port. Notches round the rim give grip. Local frame: the front face at
// z = 0, so it prints front face down.

module dial(open) {
  difference() {
    cylinder(d = dial_d, h = dial_t, $fn = 96);
    translate([0, 0, -0.01]) cylinder(d1 = 6.4, d2 = 3.4, h = 1.5);
    translate([0, 0, -1]) cylinder(d = bolt_d, h = dial_t + 2);
    rotate(open ? 0 : 180) translate([-da, -da, -1]) linear_extrude(dial_t + 2) polygon(win);
    for (i = [0 : 11]) rotate(i * 30) translate([dial_d / 2 + 0.6, 0, -1]) cylinder(d = 3, h = dial_t + 2);
  }
}

module dial_placed() {
  multmatrix([[1, 0, 0, pvx], [0, 0, -1, Sy], [0, 1, 0, pvz], [0, 0, 0, 1]]) dial(false);
}

// ---- Lid ----

module lid_shell() {
  difference() {
    translate([0, 0, zc]) hull() {
      linear_extrude(0.01) inset2d(seam_ch);
      translate([0, 0, seam_ch]) linear_extrude(lid_h - seam_ch - top_ch) outer2d();
      translate([0, 0, lid_h - 0.01]) linear_extrude(0.01) inset2d(top_ch);
    }
    translate([0, 0, zc - 1]) linear_extrude(lid_cav + 1) inset2d(wall);
    // recess for the lip of the base
    translate([0, 0, zc - 1]) linear_extrude(lip_h + 0.3 + 1) ring2d(wall - lip_t - lip_c, wall + 0.01);
  }
}

// The tongue is the outer skin of the lid front, carried on down past the rim into
// the recess of the base. Its hook rides over the lead-in and catches in the pocket.
module latch_tongue() {
  zt = zc - latch_drop;
  translate([Sx / 2 - latch_w / 2, 0, 0]) rotate([90, 0, 90]) linear_extrude(latch_w) {
    translate([Sy - tongue_t, zt]) square([tongue_t, latch_drop + 4]);
    polygon([[Sy - tongue_t + 0.01, zt], [Sy - 2.7, zt + 1.1], [Sy - 2.7, zt + 1.3], [Sy - tongue_t + 0.01, zt + 2.4]]);
  }
}

// Two slits and a relief behind the tongue free its upper 4 mm from the lid wall,
// so it flexes over latch_drop plus 4 mm.
module tongue_relief() {
  for (s = [-1, 1]) translate([Sx / 2 + s * (latch_w / 2 + 0.3) - 0.3, Sy - wall - 1, zc - 1]) cube([0.6, wall + 2, 5]);
  translate([Sx / 2 - latch_w / 2 - 0.01, Sy - wall - 1, zc - 1]) cube([latch_w + 0.02, wall + 1 - tongue_t, 5]);
}

function bat_x(i) = Sx / 2 + (i - (battery_count - 1) / 2) * bat_pitch;

// Batteries stand on their side, thickness across x, plug end along y. Two pairs of
// arms per battery, 20 mm either side of the middle so every length of the family
// spans them, each with a 45 degree bump that snaps over its free edge.
module bat_clips() {
  if (battery_count > 0)
    for (i = [0 : battery_count - 1], yc = [Sy / 2 - 20, Sy / 2 + 20], s = [-1, 1]) {
      f = bat_x(i) + s * (battery_t / 2 + bat_clr);
      zb = pb - battery_w - 0.15;
      translate([0, yc + arm_w / 2, 0]) rotate([90, 0, 0]) linear_extrude(arm_w) {
        translate([s < 0 ? f - arm_t : f, pb - battery_w - 1.6]) square([arm_t, battery_w + 1.6 + 0.01]);
        polygon([[f + s * 0.01, zb], [f - s * bump, zb - bump], [f + s * 0.01, zb - 2 * bump]]);
      }
    }
}

module lid() {
  difference() {
    union() {
      lid_shell();
      knuckles(true);
      bat_clips();
      latch_tongue();
    }
    tongue_relief();
  }
}

module lid_print() {
  translate([0, Sy, zc + lid_h]) rotate([180, 0, 0]) lid();
}

// ---- Ghost contents ----

module ghost_whoop() {
  color("Gainsboro", 0.5) translate([wcx, wcy, fz + w_floor]) {
    for (sx = [-1, 1], sy = [-1, 1]) translate([sx * sq_s / 2, sy * sq_s / 2, 0])
      difference() { cylinder(d = dd, h = fh); translate([0, 0, -1]) cylinder(d = dd - 3, h = fh + 2); }
    translate([-12, -16, 0]) cube([24, 32, whoop_h]);
  }
}

module ghost_charger() {
  color("OrangeRed", 0.5) translate([ct_x0 + x_o, ct_y0 + y_fc - cl, fz + ct_floor]) cube([cw, cl, chh]);
}

module ghost_batteries() {
  if (battery_count > 0)
    color("DimGray", 0.6) for (i = [0 : battery_count - 1])
      translate([bat_x(i) - battery_t / 2, Sy / 2 - battery_l / 2, pb - battery_w]) cube([battery_t, battery_l, battery_w]);
}

// ---- Test coupons ----

module coupon(lo, hi) {
  translate(-lo) intersection() { children(); translate(lo) cube(hi - lo); }
}

module test_layout() {
  g = 50;
  cx = wcx + r_n / sqrt(2);
  cy = wcy + r_n / sqrt(2);
  // hinge, base and lid half
  coupon([hinge_in - 16, -hk - rk - 1, zc - 14], [hinge_in + 16, 6, zc + lip_h + 1]) base();
  translate([0, 22, 0]) coupon([hinge_in - 16, Sy - 6, 0], [hinge_in + 16, Sy + hk + rk + 1, lid_h + 12]) lid_print();
  // latch, base and lid half
  translate([g, 0, 0]) coupon([Sx / 2 - 16, Sy - 7, zc - latch_drop - 8], [Sx / 2 + 16, Sy + 0.1, zc + lip_h + 1]) base();
  translate([g, 22, 0]) coupon([Sx / 2 - 16, -0.1, 0], [Sx / 2 + 16, 7, lid_h + latch_drop + 1]) lid_print();
  // the dial in its piece of front wall, and the dial
  translate([2 * g, 0, 0]) coupon([pvx - 21, Sy - 4, max(0, pvz - 21)], [pvx + 21, Sy + 0.1, pvz + 21]) base();
  translate([2 * g + 21, 30, 0]) dial(false);
  // a jaw and a piece of the inner channel with the rim
  translate([3 * g, 0, 0])
    coupon([ct_x0 + 22, ct_y0 + D - 40, fz], [ct_x0 + ct_w + 0.1, ct_y0 + D - 14, fz + ct_floor + 1]) charger_tray();
  translate([3 * g + 8, 34, 0]) jaw();
  // one whoop catch with a piece of pocket wall
  translate([4 * g, 0, 0]) coupon([cx - 10, cy - 10, fz], [cx + 10, cy + 10, fz + wt_h]) whoop_tray();
  // one battery clip
  if (battery_count > 0) {
    yc = Sy / 2 - 20;
    bx = bat_x(0);
    translate([4 * g, 26, 0])
      coupon([bx - bat_pitch / 2 - 1, Sy - yc - arm_w / 2 - 4, 0], [bx + bat_pitch / 2 + 1, Sy - yc + arm_w / 2 + 4, lid_h + 1]) lid_print();
  }
}

// ---- Layout ----

module assembly() {
  color(color_case) base();
  color(color_case) whoop_tray();
  color(color_case) charger_tray();
  color(color_case) jaws_placed();
  color(color_case) dial_placed();
  if (show_contents) { ghost_whoop(); ghost_charger(); }
  // lid swung open flat behind the base
  translate([0, -hk, zc]) rotate([180, 0, 0]) translate([0, hk, -zc]) {
    color(color_case) lid();
    if (show_contents) ghost_batteries();
  }
}

if (test_print) color(color_case) test_layout();
else if (part == "base") color(color_case) base();
else if (part == "lid") color(color_case) lid_print();
else if (part == "whoop_tray") color(color_case) translate([-wt_x0, -wt_y0, -fz]) whoop_tray();
else if (part == "charger_tray") color(color_case) translate([-ct_x0, -ct_y0, -fz]) charger_tray();
else if (part == "jaws") color(color_case) jaws_flat();
else if (part == "port_dial") color(color_case) dial(false);
else assembly();