This is the sort of tool that changes how a modelling session feels. Pick a hole edge or a shaft end, and the workbench drops a correctly sized bearing straight onto it: a 608 fits a 22 mm hole or an 8 mm shaft with no manual measuring. It is free and open source under GPL-3.0-or-later.
The catalog side is broad. Supported types cover deep-groove ball, angular-contact, self-aligning double-row, cylindrical roller and needle roller, plus AXK thrust needle assemblies and LM linear bushings. Every bearing can be set to Open, Z, ZZ or 2RS closures, with Envelope, Standard and Detailed levels of detail, flanged outer rings and flipped orientations. A Find Bearing panel searches catalog databases by designation or dimensions, a BOM tool gathers bearings, bushings, printable races and loose steel balls into a spreadsheet or CSV, and a groove feature cuts raceway profiles directly into an existing solid body.
The printable side is what stands out for me. TwoCalipers generates these parametrically as PartDesign bodies for races, snap-in cages and balls, and keeping everything inside PartDesign seems a smart call since the features stay editable rather than frozen. The maker does recommend buying commercial precision steel balls rather than printing them, and that reads as a sensible caution to me.
On quality, the project carries 95 unit tests plus GUI smoke tests and was tested with FreeCAD 1.1. The open question is platform coverage: only macOS has been tested so far, and the maker asks Windows and Linux users to report issues on GitHub. A standalone macro for the printable bearing is also published on its own.
Project by TwoCalipers. Watch it on their YouTube channel: