Yoyo Designer

Does anyone here know of a FREE Yoyo Designer that I could try out?

If you mean CAD software, a simple forum search could help you find what you need.

the search function does wonders.

Geometrically a yoyo is basically just a solid of revolution from a compound parametric curve, which I suppose is simple enough to be drawn in basically any 3d modeller.
I remember sketchup and blender as being free but there might be better ones that i dont know

Tinkercad and adobe 123 are easy and complex enough to design a yoyo

There are no dedicated yoyo design programs. What you are looking for is a CAD program. A Google search of “free cad” will do.

I use emachineshop I’m not sure if other cad softwares let you do this but emachineshop lets you select your own materials including 6061 and 7075 aluminum, delrin/acetal, titanium and more
I tried to use sketchup and it confused me

Autodesk if you want to try it out