I have designed and made these shelf brackets to be used with Electrical conduit/ EMT tubing.
The idea of the design was that i could make the bracket as large or small as I wanted, for different sized shelves.
This shelf is 1070mm x 550mm and VERY strong.
I printed the parts using PETG, I then drilled through the printed part and the metal tube with a 3.5mm hss drill bit, and finally, tapped the holes to suit a 4mm thread. (Had some 4mm thread bolts laying around)
You will NEED to resize in your slicer!!!!!
For 25mm OD tube i had to increase the size to 102%
P.S Please excuse my messy desk.