Gravity sketch is finally free, VR sculpting/cad tool
https://uploadvr.com/gravity-sketch-free-art/
https://store.steampowered.com/app/551370/Gravity_Sketch/

Haven't tried it yet, but I do think precise VR cad or even just box modeling is an underserved market, vs all the VR sculpting tools out there. I just want blender edit mode in VR.