15x15 dummy cam holder for square round tubes aluminium profil

15x15 mm system for square round tubes from DIY store
Inside Dimension = 15.5 * 15.5 mm
Nut Size M5, M3
Nut internally
Easily printable.
For the framework are 0.8 mm shell and 25% filling enough.
For aluminum hollow section profile is the weak point.
Tighten the screw only slightly.