Design a tray around what goes inside

Understand the change

1. Measure the contents

   Measure width, depth and height at the widest points, including protrusions. Use the example values only until you have an actual object.

2. Build from the inside out

   At 0.4 mm per side, the interior is 60.8 × 20.8 mm. Two 2 mm walls make the outside 64.8 × 24.8 mm. The 2 mm base makes the total height 12 mm.

3. Compare fit samples

   Set coupons to true and inspect the three shallow samples, left to right: 0.2, 0.4 and 0.6 mm per side. If printing, keep material and settings the same, identify each sample and test the real object.

4. Transfer the result

   Record which sample fits, including whether the object can be removed comfortably. Apply that measured allowance to the full tray and retain the file for the Gridfinity handoff.

Design an open tray for an example 60 × 20 × 10 mm object. Give clearance per side, wall and base thickness named parameters. Derive the outer dimensions from the inside. Add a coupon mode that makes three shallow fit samples at 0.2, 0.4 and 0.6 mm per side. Keep these as experimental allowances, not proven printer tolerances.

part_w = 60; part_d = 20; part_h = 10;
clearance = 0.4; wall = 2; base = 2;
coupons = false;
module tray(c, inside_h) {
  inside_w = part_w + 2*c;
  inside_d = part_d + 2*c;
  assert(part_w > 0 && part_d > 0 && inside_h > 0);
  assert(c >= 0 && wall > 0 && base > 0);
  difference() {
    cube([inside_w+2*wall, inside_d+2*wall, inside_h+base]);
    translate([wall, wall, base])
      cube([inside_w, inside_d, inside_h+1]);
  }
}
if (coupons) {
  for (i=[0:2])
    translate([i*(part_w+2*wall+2*0.6+5), 0, 0])
      tray([0.2,0.4,0.6][i], 3);
} else {
  tray(clearance, part_h);
}