Excellent! And seems free! :) Export 3D from the view 3D!
Import export 2D works fine with MOi (drawing scale to regulate)
I can't exit from the 2D drawing arbitrary polygon!!! (maybe i miss something but...
Edit : I have found! You must last click near the first start segment extremity!!! :)

Exists in local as 4MDS https://me.stonybrook.edu/software/

You have an another free simulator more versatile but only 2D: Algodoo! ;) http://www.algodoo.com (not shown following)

Motion Gen