I designed this to be a stronger than the others I have downloaded and to work with a 12x1mm copper tubing that you find in a harware store.
Print it as strong as possible. I printed it using PLA 3 perimiters and 15% infill with 0,25mm layer height.
Glue the pipes with epoxy and you ate good to go.
I used a 9,5mm drill bit (Kreg style) from and regular screws 4,5mm (shown in picture)