A two-part protective case shaped around your model: each half carries an impression of the part, so it is held on every face and cannot move in transit. Print both halves, put the part in, tape or band it shut, and post it.
This is what you want when the thing you are shipping is fragile, oddly shaped, or valuable enough that loose packing peanuts are not good enough.
This is the setting that decides whether the case works.
| Clearance | Result |
|---|---|
| Too tight | The part will not go in, or you force it and damage what you are protecting |
| About right | The part seats with light pressure and does not rattle |
| Too loose | The part moves in transit, which is the whole thing you were preventing |
A small amount of clearance plus a wrap of tissue or foam beats a very tight fit: the padding absorbs shock, and a hard case pressing directly on a fragile part can be worse than no case at all.
| Setting | Use | Why |
|---|---|---|
| Material | PLA is fine, PETG is tougher | PETG absorbs a drop better; PLA is stiffer and cheaper |
| Walls | 3 perimeters | The case has to survive being dropped, not hold liquid |
| Infill | 10 to 15% | Light matters here, postage is by weight |
| Layer height | 0.2 to 0.28 mm | Nobody is looking at the finish; print it fast |
| Supports | None | Each half prints flat side down |
Print it fast and light. This is packaging, not a display piece, and both filament and postage cost real money per shipment.
Clearance too tight, or the model you uploaded is not quite the model you printed. Increase the clearance and check you used the same file at the same scale.
Too much clearance. Reduce it, or add a wrap of tissue, which is the cheaper fix and also adds shock absorption.
They are designed to be taped or banded rather than to latch. Two bands at right angles hold better than tape alone, and survive a sorting machine.
Drop the infill to 10%, thin the walls, and print in PLA. A packaging insert is one of the few prints where being light is worth more than being strong.