Here's my VIRB to bar adapter. It's done in OpenSCAD so it's fully parametric if you need to tweak it. Also the VIRB mount is a separate module so if you need to print a VIRB mount on top of a lego brick or a Yoda head, knock yourself out.
https://www.youmagine.com/designs/ga...unt-parametric
As always, my stuff is CC0 public domain licensed.