About this project
A small lidded round box with a screw-on knob — the kind of thing that ends up holding rings, pills, guitar picks or a spare set of screws.
Box and lid
The body is a plain hollow cylinder with rounded outer edges. The lid sits on top and is kept from sliding off by an inset ring that drops down inside the opening.
That inset is where the fit lives. Its clearance is radial — 0.4 mm gives a lid that drops on and lifts off cleanly; tighten it toward 0.15 for a lid that stays put when the box is tipped, and expect to sand it if your printer runs tight. The inset depth is how far it reaches down: deeper resists being knocked sideways, at the cost of interior height.
Lid lift is the visible gap between body and lid in the scene. It is a viewing offset, not a fit parameter.
The knob
The knob screws into the lid on its own small thread rather than being printed as one piece. Two reasons: the lid prints as a flat disc with no overhang, and you can print knobs in a different colour or swap them later.
Thread engagement has to stay inside the lid disc, which the design check enforces — there is nothing above the lid for the thread to cut into. A 1 mm pitch on a 4.75 mm thread is about the finest worth printing; go coarser if your printer struggles.
Trim rings
Optional torus rings around the top and bottom edges of the body and around the lid. They are what makes this the fancy version rather than a plain round box — purely decorative, and they cost nothing to print since they sit on outside edges.
Printing
Three parts: body, lid disc, knob. All print flat with no supports. The knob thread is small, so slow it down and print it with a fresh nozzle if you want it to bite properly on the first try.