I think it may be relevant here, we are working on something called Buerli: http://buerli.io We are just wrapping up and plan to release - everything is working as expected but it’s marketing and security that we’re trying to complete. Solid modelling will be completely free. This doesn’t just do basic booleans but pretty much everything that a real, parametric CAD can do: sketches, nurbs, constraints, extrusions, revolves, blends, slices, etc. At the same time it’s tied into threejs as you see in these screenshots, you can use three-paths for instance.
if you need it quickly, you could write us for beta access.