Die Cut Foam Inserts: How to Protect Your Product Inside the Case
Published October 24, 2026
A hard shell protects a product from the outside. The foam insert protects it from the inside. If a product can move inside its case, it gets scratched, shaken and knocked against the shell every time the case is carried. A die cut foam insert holds the product in a fixed place. This guide explains how inserts work, which foam to choose, and what to send us when you order.
What the insert does
The insert has four jobs. It holds the product still, so the product cannot slide or rattle. It absorbs shock, because the foam compresses at the points where a drop would hit hardest. It keeps parts apart, so a device, its charger and its cable do not rub against each other. And it presents the product. When the case opens, every item sits in its own place, which matters for retail products and for tools that a technician checks at a glance.
Insert materials: EVA foam and PU sponge
Most inserts we cut are EVA foam, the same family of material as the shell. EVA foam is a closed cell foam. It is firm, it holds the cut shape for years, its edges cut cleanly, and it does not absorb water. It suits heavier products, sharp edged products and anything fragile that needs a firm pocket.
PU sponge is an open cell foam. It is soft, light and lower in cost. It works as padding for light products and as a soft layer under a product. Its limits are that it compresses flat over time, tears more easily than EVA foam, and absorbs water if it gets wet. For a light product that ships once and sits in a drawer, PU sponge can be the right choice. For a product that travels daily, we recommend EVA foam.
Two other options come from the same workshop. CNC cut foam is milled instead of die cut, which suits complex shapes and small runs. A molded EVA tray is thermoformed like the shell, which suits a fixed product set that must look the same in every unit.
How die cutting works
Die cutting starts with the outline of your product. The layout is drawn with a pocket for the product and separate pockets for each accessory. A steel rule die is then made to that drawing. The die is a board with a shaped metal blade that follows every pocket outline. In the press, the die comes down on the foam sheet and cuts the full layout in one pass.
Depth is built in layers. If a product is tall, two or three cut layers are bonded together so the pocket is deep enough. Finger notches are added at the sides of a pocket, so the user can lift the product out. The first inserts are always test fitted with the real product at the sample stage, and the die is adjusted before bulk production if the fit is too tight or too loose.
What to send us when you order
The best input is the product itself. Send one unit to the factory, and we measure it and test the fit directly. If you cannot send the product, send a drawing with outside dimensions, the weight, and a note on the fragile points, for example a screen, a lens or a thin housing. Also send the list of accessories that share the case, and tell us if the case is the retail packaging or only transport protection. With that, the insert layout is confirmed at the design stage, before the die is cut. MOQ is 500 pcs and samples take 1 to 3 weeks.
How the insert and the case work together
The insert is sized to the inside of the shell, so the two are quoted and made as one product. The lid of the case can carry a mesh pocket or elastic straps for cables, papers and small parts that do not need a shaped pocket. When you approve the sample, check the fit with the product inside and the case closed. A good insert holds the product with the case open and upside down, and the zip still closes without force.
Inserts are made with the case in these product lines: EVA Hard Cases and Tech Organizers and Cable Cases.