Augmented Reality Design Tools. I need your help!

Well there is Gravity Sketch and it seems fantastic. You sketch in 3D VR/AR space and it can output meshes but also STEP surfaces which is great for your workflow. You do need a laptop/PC with very specific specs including the Windows 10 Creators update so check it out both for Gravity Sketch and the Oculus/WMR/HTC Vive it is compatible with.