There is Art of Illusion recommended on this site.
Plus a number of free softwares listed in this article: https://all3dp.com/1/free-3d-modeling-s ... re-3d-cad/
I tried a number of them, some doesn't work on my computer (low end Intel graphics card), some are broken (bad registration process), I was a bit successful with Art of Illusion (after deactivating OpenGL), DesignSpark Mechanical (made a primitive cheminey with it), I plan to try Wings 3D.