This may not look impressive, but I created it in virtual reality using an HTC Vive and an app called SculptrVR. It was pretty amazing to be able to build an object floating in mid air and walking around it.
Here's a video (not of me) showing how SculptrVR works: https://youtu.be/8HgpL5-e1LM
It wasn't immediately clear how to export scenes from SculptVR. Turn your left hand palm up to see the secondary menu where you can save, save to obj, etc using right hand to point at buttons. (also there's no confirmation when you save)
The obj file then gets saved to: C:\Program Files (x86)\Steam\steamapps\common\sculptrvr\SculptrVR\SculptrVRSaves
It saves in inches so when you re-save it as an stl make sure you convert from inches to mm or else it will be tiny.