Origami sleeve wallet, folded from one flat print

// A card sleeve wallet printed as one flat sheet a few layers high and folded like a
// paper kit. Panels are stiff, fold lines are thin bands that bend around the stack of
// cards. Side flaps lock into slits with arrow tabs, so it needs no glue.
// Everything folds toward the top of the print: the bed side becomes the outside.

/* [Wallet] */
// Number of cards it should hold.
cards = 5; // [2:1:8]
// Extra room for folded bank notes, in mm.
cash_room = 1; // [0:0.5:3]
// Envelope flap that closes the top.
closing_flap = true;

/* [Print] */
// Thickness of the panels. Three layers of 0.2.
panel_thickness = 0.6; // [0.4:0.1:1.2]
// Thickness of the fold lines. Two layers of 0.2.
fold_thickness = 0.4; // [0.12:0.02:0.6]
// Room around a card, per side.
card_play = 1; // [0.5:0.25:2]

/* [Preview] */
// 0 is the flat sheet you print. 100 shows it folded.
fold = 0; // [0:5:100]

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

/* [Hidden] */
$fn = 48;
card_w = 85.6;
card_h = 54;
card_t = 0.76;

t = panel_thickness;
ft = min(fold_thickness, t);
W = card_w + 2 * card_play;          // back panel
H = card_h + 2 * card_play;
Wf = W - 1.5;                         // front panel, clear of the side folds
Hf = H - 1;
inner = cards * card_t + cash_room + t;   // pocket thickness, the tabs lie inside too
s_front = inner + 2 * t;              // fold band around the cards
s_side = s_front + t;                 // around the cards and the front panel
s_lid = s_side + t;                   // around the side flaps as well

r = 3;            // corner radius of the panels
edge = r + 1;     // folds stop this far from a corner
flap_w = 18;
flap_taper = 8;
lid_h = 22;
lid_taper = 14;
neck_w = 12;
neck_l = 2.5;
head_l = 9;
barb = 2;
tip_w = 4;
tongue_w = 20;
tongue_l = 10;
slit = t + 0.6;
push_r = 9;

A = 90 * fold / 100;   // each fold band turns 90 degrees at both of its edges
D = 20 * fold / 100;   // tabs dive through their slit

echo(str("Flat sheet: ", W + 2 * (s_side + flap_w + neck_l + head_l), " x ",
  H + s_front + Hf + (closing_flap ? s_lid + lid_h + tongue_l : 0), " mm"));

// ---- 2D helpers ----
module rounded(rad) { offset(r = rad) offset(delta = -rad) children(); }

// A slot with round ends, long side along x.
module slot(l, w) {
  hull() for (s = [-1, 1]) translate([s * (l - w) / 2, 0]) circle(d = w);
}

// Hole through the bottom fold to push the cards up.
module push_hole2d() { translate([0, -s_front / 2]) circle(r = push_r); }

// ---- Panels, in print coordinates ----
module back2d() {
  difference() {
    rounded(r) translate([-W / 2, 0]) square([W, H]);
    push_hole2d();
  }
}

module front2d() {
  difference() {
    rounded(r) translate([-Wf / 2, -s_front - Hf]) square([Wf, Hf]);
    push_hole2d();
    // thumb notch in the top edge
    translate([0, -s_front - Hf - 3]) circle(r = 11);
    // slits for the side tabs
    for (s = [-1, 1])
      translate([s * (W / 2 - flap_w - 0.2 - slit / 2), -s_front - H / 2])
        rotate(90) slot(neck_w + 1.5, slit);
    // slit for the closing tongue
    if (closing_flap)
      translate([0, -s_front - (H - lid_h - 0.2 - slit / 2)]) slot(tongue_w + 1, slit);
  }
}

module band_front2d() {
  difference() {
    translate([-Wf / 2 + r, -s_front - 0.05]) square([Wf - 2 * r, s_front + 0.1]);
    push_hole2d();
  }
}

// Right side, the left is its mirror.
module band_side2d() { translate([W / 2 - 0.05, edge]) square([s_side + 0.1, H - 2 * edge]); }

module flap2d() {
  x0 = W / 2 + s_side;
  hull() {
    translate([x0 - 0.01, edge]) square([0.02, H - 2 * edge]);
    for (y = [edge + flap_taper + 2, H - edge - flap_taper - 2])
      translate([x0 + flap_w - 2, y]) circle(r = 2);
  }
}

module tab2d() {
  x1 = W / 2 + s_side + flap_w;
  hw = neck_w + 2 * barb;
  translate([x1 - 0.01, H / 2 - neck_w / 2]) square([neck_l + 1, neck_w]);
  hull() {
    for (s = [-1, 1]) translate([x1 + neck_l + 0.75, H / 2 + s * (hw / 2 - 0.75)]) circle(d = 1.5);
    translate([x1 + neck_l + head_l - tip_w / 2, H / 2]) circle(d = tip_w);
  }
}

module band_lid2d() { translate([-(W / 2 - edge), H - 0.05]) square([W - 2 * edge, s_lid + 0.1]); }

module lid2d() {
  yb = H + s_lid;
  a = W / 2 - edge;
  hull() {
    translate([-a, yb - 0.01]) square([2 * a, 0.02]);
    for (s = [-1, 1]) translate([s * (a - lid_taper - 3), yb + lid_h - 3]) circle(r = 3);
  }
}

module tongue2d() {
  ye = H + s_lid + lid_h;
  hull() {
    translate([-tongue_w / 2, ye - 0.01]) square([tongue_w, 0.02]);
    for (s = [-1, 1]) translate([s * (tongue_w / 2 - 4), ye + tongue_l - 4]) circle(r = 4);
  }
}

// ---- Folding ----
module ext(h) { linear_extrude(height = h) children(); }
// Turn the children around a fold line on the bed: along x at height y, or along y at x.
module hinge_x(y, a) { translate([0, y, 0]) rotate(a = a, v = [1, 0, 0]) translate([0, -y, 0]) children(); }
module hinge_y(x, a) { translate([x, 0, 0]) rotate(a = a, v = [0, 1, 0]) translate([-x, 0, 0]) children(); }

module side() {
  hinge_y(W / 2, -A) {
    ext(ft) band_side2d();
    hinge_y(W / 2 + s_side, -A) {
      ext(t) flap2d();
      hinge_y(W / 2 + s_side + flap_w, -D) ext(t) tab2d();
    }
  }
}

module wallet() {
  ext(t) back2d();
  hinge_x(0, -A) {
    ext(ft) band_front2d();
    hinge_x(-s_front, -A) ext(t) front2d();
  }
  side();
  mirror([1, 0, 0]) side();
  if (closing_flap)
    hinge_x(H, A) {
      ext(ft) band_lid2d();
      hinge_x(H + s_lid, A) {
        ext(t) lid2d();
        hinge_x(H + s_lid + lid_h, D) ext(t) tongue2d();
      }
    }
}

color(color_wallet) wallet();