This part is a remix from this rial bracket: https://www.thingiverse.com/thing:4435764
I put the clamp in to a box, added Thread Inserts and a strain relief.
Printing:
Parts using Inserts:
Parts using wood screws:
Please note that the pillars from the m3f files are modifiers for the infill and not solid objects.
The author hasn't provided the model origin yet.