A torque wrench set came back to our sample bench in Gaobu last month with a complaint attached: two of the 24 sockets had worked loose in transit and the drive tips were chipped. The shell was undamaged. The interior was not. That is how most custom tool case projects actually start - not with the outer material, but with a layout that was drawn before anybody measured the tools.
Start with the tool list, not the shell
Before any foam is cut we ask for the physical kit, or at minimum a dimensioned list with photographs. Every slot is drawn from the real part plus clearance: 2-3 mm on the sides for a tool you pull out every day, 4-5 mm for anything handled in a glove. A 1/2 inch drive socket needs a different finger relief than a 4 mm hex bit, and putting both in one row is the usual reason tools get forced back in sideways and the foam tears at the corner. Cardboard mock-ups still beat renderings at this stage: the sample room cuts a full-size tray from 3 mm board, the client drops the real tools in, and we photograph the gaps. Roughly one layout in four comes back for a second version, usually because a battery pack or a pistol grip was taller than the spec sheet said.
Choose the insert: die-cut foam, egg-crate, or a moulded tray
Three constructions cover most of what we build for our EVA tool case line:
- Die-cut foam: EVA or PE sheet at 25-40 kg/m3, cut on a vibrating-blade table or a steel rule die. Kerf runs around 1.2 mm and slot tolerance is held to about +/-0.5 mm on repeat orders.
- Egg-crate lid foam: 20-25 mm convoluted PU or PE glued into the lid, holding tall parts down rather than sideways and absorbing the 5-10 mm of height variation you almost always get across a mixed kit. Where a kit ships in the thousands, a thermoformed 0.8-1.2 mm PET or ABS tray drawn over an aluminium tool gives a rigid pocket that will not crush in a hot container. Two-tone lamination - 3 mm black over a 2 mm orange base - is worth the extra step for service kits: a missing 10 mm spanner shows as an orange rectangle visible from a metre away, which is what maintenance crews ask for when the case is audited at the end of a shift.
Fit checks before the tooling is cut
A layout that looks right on the bench can still fail inside a carton. We run the loaded case through a 1.0-1.5 m drop on all six faces, three drops per face, following ISTA 2A practice for parcels under 23 kg (about 50 lb). Zippers are cycled 5,000 times on a fixture because the zipper is usually the first thing to go, and a split slider empties a tray faster than any drop. Clients who move palletised freight often ask for ASTM D4169 instead, and both protocols are run with the real tools inside, not sandbags.
Interior tooling for a die-cut layout is a cutting file, not a mould, so revisions stay cheap and fast: about 3 days for a first sample on a standard structure, longer if the shell itself needs a new compression tool. MOQ starts at 500 pieces with tier pricing at 500 / 1,000 / 3,000, and buyers who want an egg-crate lid plus a die-cut base usually land in the 1,000-piece tier because lamination is set up in batches. Material and insert choices are listed under customization options if you want to price two versions side by side. Send the tool list and one photo of the kit laid out on a bench to lucy@lianpingbag.com through the contact page and we will cut the cardboard version first. The diesel injector kit currently on the bench goes back to Germany on Thursday with a 4 mm taller finger relief on the top row.