This Z brace is for the Sidewinder X1 and uses 15mm(UK) or 16mm(1/2"US) copper gas/water pipe 600mm long on each side. I used 10mm M5 screw for the top brackets and 10mm M4 screws and nuts on the clamps.. 12mm M4 on the rear brackets.
I used PLA without any problem but PETG would probably be better
Technical
The base plate can be superglued to the bottom clamp.
The top clamp can be tricky to locate. If the belt is loose then make sure the clamp is correctly on the Sidewinder top plate, and use slight outward force when tightening the screws.