I really love the concept behind Eric's Z Axis Coupler, but i really love the looking of the sandwitch style couplings. So i decided to make the fusion between them. I hope you like the concept. If you need other dimentions let me know. But i will add them later anyway. The internal hole has a conic shape so the grip is solid. 5x5= 31x20x21 8x5=31x20x21 If something is labeled as test it means it should work, but i did not print that yet. You need 2 x Znuts, , 4 of 3mm screw, 4 of 3mm nuts Best print for me is with the internal side of the coupling laying on the bead.