Annular snap-fit

A beaded plug and a grooved ring — the round snap joint.

The annular snap is the round sibling of the cantilever snap. A post carries a raised bead near its tip; the receiving ring has a narrower bore and an internal groove. Pushing the post through the bore deflects the bead until it springs into the groove and is retained — the joint used for pen caps, bottle caps, and round enclosures. Retention is purely geometric: the bore is narrower than the bead so it can’t pull back out, and the bead protrusion must exceed the clearance gap or nothing would hold. Both parts are laid out to print flat.

1. Open the Generate panel from the left sidebar and choose Annular snap (under Enclosures).
2. The plug and ring drop in side by side as editable parts. The parameters open in the Properties panel, where you set them.
3. Set the post radius and height and the bead protrusion and thickness, then pick a fit — or Custom to set the snap gap yourself.
4. Set the ring wall thickness (leave the ring on to get the receiving part too).