If anyone would like to plug the ends of your gMax's 1.5" x 1.5" aluminum extrusions, here you go.
You can download it here:
http://www.thingiverse.com/thing:1398110
For mine I used Simplify3D 0.14 resolution.
You can download it here:
http://www.thingiverse.com/thing:1398110
For mine I used Simplify3D 0.14 resolution.