US 50 or 25mm circulat knitting needles

thingiverse

Print two sets of everything using your provided STL files or modify the design if you'd like to with Autodesk Inventor. Take the first assembly part (Tip 1), carefully slide it into one of the tubes. Thread a wire or string through the whole on top of the second Tip 2 part, and make sure the knot at the end is tight enough that the string cannot come back out. Place this setup into the tube on the other side from where you placed the first Tip 1 piece. Take another wire or string thread it all the way through the other end on the same tip 2 you've just been working with and also place a secure knot so your wire does not fall back through the tubing.