I tried FreeCAD and the user interface is so unintuitive and things just have constraints that block you from doing the most basic things from the get-go that I just gave up in 10m, like sibling. SCAD is scripted/programmer CAD, I like the concept and have used for a few things but it's quite a learning curve to do anything more than a cube with some funny edges! Dune3D is currently my go-to for 3d-printer related parts!