This is a replacement lid for Timemore's Chestnut C2/C3 coffee grinder as the original has a tendency to break after some time.  I recommend one of the 46mm variants in order to minimize the amount of microplastic in your coffee. The remaining gap of 0.5 mm is barely noticeable anyway, though I won't stand between you and 46.8 mm variants if the perspective of a visible gap drives you up the wall.

The non-flat variant was designed to be as close as possible to the original one. I only added a rounded conical profiling of the mounting hole (invisible after the installation) and increased the number of cutaways on a “chuck” from 3 to 5 in order to avoid breakage during the assembly process.

Repair instruction

The crank cannot be unscrewed! The parts are joined by a rivet. Just break away the (already broken) lid and press-fit the new one. The tolerance is just right assuming that you account for material shrinkage in your slicer of choice (I've designed this part with 0.1 mm of tolerance). Press on the lid from opposite sides at the same time otherwise it can break when moving through the  flange on the shaft.

For support-free FDM printing use the flat type.

For tight fit use 46.8 mm version.

Suggested material: PETG (for abrasion resistance) 

Suggested infill: 30%

• 2D Honeycomb for a more stiff variant;
• Gyroid for a more flexible variant (decrease the amount of top layers to 2 and bottom layers to 3).

Print on the flat side.