Sixty seconds on the compression rig: a finished shell sits under 50 kg of steel plate, gets released, and then gets inspected for any permanent crease across the bridge. Eyeglass cases fail this check in a way that surprises buyers, because failure is rarely a crack. It is a crease that presses into the temples every time somebody sits on the case.
The failures nobody plans for
Three things wreck glasses inside a carrier. Pressure landing on the temples, which slowly springs the hinges. Grit trapped in the lining, which leaves a fine arc of scratches across the lens. And a case carried loose in a bag, compressed against everything else in there. Designs that hold up put load onto a raised bridge block and the rim channels instead of the lenses, keep the lining clean-finished with no seam running across the lens area, and add a carabiner loop or belt attachment so the case stops travelling loose.
What goes inside the shell
Lining choice is a trade-off between feel, lint and heat. Flocked tricot is cheap and matte but can mark when the case sits in a hot car; velvet reads more premium and resists rub marks, which is why it turns up in watch and gift presentation; a microfibre section makes sense for the cleaning cloth pocket. A typical optical specification is a 3 to 4 mm shell wall, velvet-faced die-cut insert, and a hidden magnet closure tuned so it opens with one hand. Add a small pocket for the cloth, because nobody ever keeps hold of those.
Beyond everyday spectacles
Prescription frames are only part of the volume. There are safety spectacles on industrial sites, whose lens geometry cannot be squeezed out of true by a soft pouch, so a rigid wall with a formed channel gets specified. Ski and swim goggles carry anti-fog coatings that need air moving over them, which makes a fully sealed case the wrong place to store anything damp and pushes those designs toward a vented shell or a mesh panel. Children's frames need a shorter cavity and a clip that survives being knocked off a desk.
Two shapes dominate the drawings that arrive here. Oversized sunglasses need a deeper draw, wider rim channels and a bridge block modelled on that frame rather than on a rectangle, otherwise the temples take the load and the hinges loosen first. Work vehicle and site cases go the other way: a belt loop or clip, a dark interior that hides workshop dust, and usually a spare cavity for the second pair of readers everyone loses track of. Construction gets settled early too: full clamshell zip, three-side zip with a fabric hinge, or a flip-top held by a hidden magnet. Retailers usually want the case to stand upright on a shelf, which means putting some flat base into the shell. The EVA eyeglasses case line covers most of those combinations, and the same forming methods carry over to the smaller shells in our cases for electronic accessories.
The job on the bench this morning is a wrap-around sports frame whose temples sit at an angle the first sample did not show, so the moulding supervisor has dropped the forming temperature another five degrees to stop the rim channel from thinning out at the bend.