Traditionally, I’ve made a post providing resources/examples, but this contest has me quite at a loss.
Often, such parts require modeling in 3D — I did that for a bracket for a lawn mower ages ago:
(referenced, w/ a link which no longer works)
Since then, I’ve gotten quite a bit better at OpenSCAD, though these days I usually use BlockSCAD as a front-end:
At:
https://www.blockscad3d.com/community/projects/2005506
in case anyone wants to dig into it — it’s one of two brackets for a plastic pipe to function as a filament stand/dispenser (along w/ some acrylic tubing I still need to cut, and some plastic washers for separation I need to print).
Or, folks could use a “real” CAD program: