I used Rhino 3D 3.0 another out dated piece.
The cube was selected from the solids as a 25.4 mm insert, then exported out as an stl file.
Sorry guys I'm 56, and everything up till now has and usually does exactly what I want.
Darn it I don't to upgrade any more.
I don't do hardcore gaming anymore so a top notch state of the art rig I don't need
Rhino 3D, Auotcad 11, and some older version of Solidworks along with any number of other softwares and internet windows all open at once do just fine.
Anyway