The shell that comes off the press at about 165 degrees C (roughly 330 degrees F) is a flat, slightly rubbery rectangle until it is trimmed, laminated and sewn. What turns that rectangle into protective packaging is everything that happens after moulding, and that sequence is where most of the technology in a modern EVA case now sits.
Compression moulding versus thermoforming
Two processes make the shell. Compression moulding presses a heated EVA sheet between matched aluminium tools; it gives a defined rim, a consistent wall, and the ability to mould in ribs, logo panels and hinge channels, and the tooling is cheap enough for a 500-piece order to carry it. Thermoforming draws a sheet over a single tool under vacuum; it is faster per part and suits large shallow trays, but the wall thins at the corners and fine detail comes out softer.
Wall thickness decides everything downstream. Most shells are built at 2.2-3.0 mm nominal with the rim section left full, and press temperature is held within about 5 degrees C, because a hotter tool gives a glossier surface and thinner corners at the same time. That is the trade-off the moulding team argues about most often.
Lamination and the interior
Protection does not come from the shell. It comes from the insert, and the current version is a laminate: a die-cut EVA or PE foam base at 25-40 kg/m3, a 20-25 mm convoluted egg-crate layer in the lid, and for fragile products a thermoformed PET tray at 0.8-1.2 mm. Digital cutting runs straight from a DXF at about +/-0.5 mm, so a revised pocket layout no longer waits on a new steel rule die.
Surface materials are picked by use case: 1680D Oxford or PU leather laminate for abrasion, velvet or brushed tricot for optics and jewellery, and for electronics a conductive lining with surface resistance in the 10^6 to 10^9 ohm range meeting IEC 61340-5-1. Our electronic accessory cases use the last of these whenever a bare board travels inside.
Testing it as packaging
A case is packaging, so it is tested as packaging. Loaded to the real weight, it is dropped from 1.0-1.5 m on all six faces, three drops per face, under ISTA 2A or ISTA 3A depending on the parcel profile, with ASTM D4169 used for palletised distribution programmes. Zippers are cycled 5,000 times because the zipper is usually the first thing to go.
Ingress ratings are verified rather than assumed: an IP54 or IP65 claim is checked in a dust cabinet and under a spray nozzle, and the zipper garage, seam binding and valve all have to survive the same cycle. For cold-chain work, as in our medical case range, the insulating layer is measured for thickness retention after compression rather than on the drawing. Options that need tooling and options that are a file edit are separated on the customization page, which is where most buyers start once they have a product drawing. The medical case going to a Japanese distributor next week carries a 3 mm insulating layer and a gel-pack pocket; its tooling plate was cut on Tuesday and the first shots are due Thursday morning.