Can the clear lid of a custom tool case be swapped for an opaque one?

Answer: Yes, same mould and a different resin, but the lid foam is redone and the rim step relaxes.

Do more cells make a custom tool case harder to close?

Answer: Yes. More dividers mean uneven shrinkage and the rim middle lifts 0.5 mm, so past eight cells add a flange.

How is the load rating of a custom tool case set?

Answer: Loaded weight times 1.5, then checked for the bottom case in a three high stack.

Does a clear lid scratch?

Answer: Polycarbonate sits near 2H and a key leaves a mark, while a hard coat lifts it to 3H.

How is a small run tooled?

Answer: Under 500 pieces, aluminium tooling runs 30,000 to 60,000 RMB for roughly 30,000 shots.

Custom tool case specifications: size, wall thickness and load

Quick answer: A custom tool case sizes from the small end up: part count sets the cells, deepest part sets the height, loaded weight sets the wall.

Custom tool case size tiers and cell counts
Clear lid thickness and light transmission
Multi cell insert depth and finger access
Load rating handle pull and stacking
Filling the specification sheet before tooling
FAQ

1. Custom tool case size tiers and cell counts

A custom tool case starts from the part count, not the outer length. Tool six parts into a four-part body and the extra cells come out too narrow for sockets, so usable volume drops near 70 percent. Cells first, then the cavity, then wall and lid height.

Tiers sit close together: every 40 mm of length adds about 30 percent volume while the wall only moves from 1.8 mm to 2.5 mm, because stiffness comes from the rim flange.

Outer mm	Cavity mm	Cells	Wall mm	Load kg
145	130x95x35	3-4	1.8	3
180	165x120x45	5-6	2.0	5
225	205x150x55	6-8	2.2	8
260	240x175x65	8-10	2.5	12

Height follows the deepest part, not the average. A 42 mm part takes a 45 mm cavity with 2 mm of lid foam compression.

2. Clear lid thickness and light transmission

The clear lid separates a custom tool case from a plain one and is easy to ruin. Polycarbonate at 1.5 mm gives 88 percent transmission and takes a 500 g ball dropped from 300 mm; polystyrene gives 90 percent and cracks.

Custom tool case in orange, lid upright, grey foam cut for a meter and cable, black gasket on the rim

Rim fit matters more than sheet thickness. A 0.3 mm step with two 2 mm dust lips presses against the inner wall and keeps dust out; push it to 0.5 mm and the latch feels stiff, which users read as broken. A clear lid cannot carry a full gasket, because it blocks the view.

3. Multi cell insert depth and finger access

More cells is not better, because clear cell width is the limit. Under 22 mm a finger cannot reach in, and going from 6 cells to 10 drops average width from 45 mm to 28 mm.

Depth is part height plus 3 mm and the finger notch is R8: under R5 there is no grip, over R12 the neighbouring divider thins. Dividers run 1.2 mm in the body material with a 0.8 mm root fillet.

Cell type	Clear size mm	Divider mm	Part length mm
Long	180x35x30	1.2	150-175
Square	70x70x35	1.5	60-68
Narrow	25x25x40	1.0	20-24

Depth also has to clear the lid foam: with 8 mm of foam, part height plus 8 mm must stay inside the cavity, or the cell floor whitens.

4. Load rating handle pull and stacking

Load runs 3 kg to 12 kg per case, each cell rated at a third. Handle pull is 150 N held 60 seconds, near double the margin over 8 kg; the 145 mm tier uses a thumb notch, because the handle root is where small cases crack first.

Custom tool case in black, close on the yellow lid and folding handle, corner ribs and grain texture

Hinges take 6000 cycles, and a 0.8 mm living hinge shows a white line by then. Two latches sit at 18 N to 25 N: under 18 N the lid springs open, over 25 N it cannot be worked one-handed. Stacking stops at three high, where the bottom lid carries 16 kg and may sink 0.5 mm in 24 hours.

5. Filling the specification sheet before tooling

Finish the sheet before the mould is cut, because a change afterwards costs tooling. Write tolerances for calipers, grams for scales and newtons for pull tests.

Field	How to write it	How to measure
Cavity	205x150x55 mm, plus or minus 0.6 mm	Calipers, three points
Wall	2.2 mm, minus 0.10 mm at most	Ultrasonic gauge, five points
Clear lid	1.5 mm, transmission 85 percent or more	Micrometer and light meter
Load	8 kg distributed for 24 hours	Sand bag loading

First article checks are three actions: weigh it, gauge the cavity, check the lid for light leaks. A 5 percent mass error means the wall drifted, a 0.6 mm cavity spread means uneven cooling.

Conclusion

Cells, depth, wall, hinge and load form one line: part count sets the cells, the deepest part sets the height, and loaded weight sets the wall the hinge must survive. Every field carries a tolerance, because 2 mm decides whether the custom tool case shuts.

This article discusses only the container (case body) side of specifications and design intent, and does not cover any handling, loading or use of the contents.