So far I have always just drawn the part in a CAD package. As a home user you can get a free licence for Fusion 360, and there are tons of tutorials on how to use it on You Tube.

Part of my worry would be that you are unlikely to get exactly what you wanted first try, so as a CAD file you can tweak the measurements and print another stab at it.

A photo of the part and we might be better able to advise.