The workshop argument started over a cracked corner. A German hand-tool brand sent us a competitor's injection-molded PP case that had split along the wheel housing after a winter delivery, and asked whether EVA would hold up better. The honest answer is that it depends on where the case spends its life, because the two materials fail in completely different ways.
Weight and what it costs to carry
A molded EVA shell at 0.18-0.22 g/cm3 and 3.5-5 mm wall thickness, laminated to 600D polyester or PU leather, typically comes in 30-40 percent lighter than a comparable injection-molded PP or ABS case. On a 400 mm tool case that is about 780 g for the plastic build against roughly 480 g for the EVA build, before tooling and contents. Over a service engineer's day, across a van and up a ladder, that difference is the reason the EVA version gets picked up and the plastic one gets left in the vehicle. EVA also stays flexible down to about minus 20 C, while general-purpose PP starts to lose impact strength near freezing and ABS grows brittle sooner again.
Dent, scratch and noise
Drop an EVA case on a corner and it absorbs the hit and springs back; drop a hard plastic case the same way and the energy goes into a stress line that shows up as a white crease or a crack. Scratches on EVA read as a scuff you can rub down; scratches on gloss ABS stay visible for the life of the case. The third difference is noise, which nobody puts on a spec sheet and every technician notices: tools rattling inside a hard shell sound loud, because the shell is a resonating box. EVA and its fabric laminate damp that, and a die-cut foam insert does the rest.
Tooling money and order size
This is where EVA usually wins the business case. An injection tool for a 400 mm case runs into tens of thousands of dollars and needs volume in the tens of thousands to amortise. A compression or thermoforming tool for the same footprint is a small fraction of that, and our MOQ is 500 pieces with tier pricing at 500 / 1,000 / 3,000. For a brand launching a new kit, or a distributor testing a regional SKU, that gap decides the project. Sampling on an EVA shell takes about three days, against weeks for a first injection shot. Our EVA tool case line is set up for exactly this pattern, with insert layouts changed between runs rather than re-tooled.
Where hard plastic still wins, in our own quoting experience, is palletised stacking. A ribbed PP case with interlocking feet will stack five or six high on a pallet without crushing the case below; a soft-walled EVA case needs shelf storage or a divider. Sealing is the other one. A gasketed injection case with a purge valve reaches IP67 and survives immersion; a sewn EVA case with a storm flap gets you splash resistance, not submersion. Chemical resistance to oils and solvents is also better on PP.
So the rule we give buyers is short. If the case lives in a van, a service bag or a technician's hand, EVA is lighter, quieter and cheaper to tool. If it lives on a pallet, under a tarp, or in the bilge of a boat, the plastic case is the right call and we will say so. Both formats run through the same incoming-material bench and the same final inspection at the Gaobu plant, with RoHS and REACH declarations issued per batch and drop checks at 1.0 m on six faces for either type.
The German brand went with EVA for the 500-piece first run and kept the injection tooling for a later, higher-volume SKU. Their next sample, a 420 mm shell with a removable bit board and a webbing shoulder strap, is on the press this week. Foam densities and layout options are listed on the customization page, and the accessory case format uses the same shell family in a smaller footprint.