My bike needed a repair, and no repair shop in my area had this tool available. Since the original is quite pricey and I was likely only gonna need it once, I decided to design a printable replacement instead. 

It uses M3 steel dowel pins for the tiny parts that transfer all the force. I used 30mm long ones - shorter ones should work just as well, but if you push them too far into the plastic you're never gonna get them back out again. 30mm pins stick out both ends, so they can be pushed back and forth if required. It also uses some 8mm rods to stabilize the upper part. I knew a Hex socket wouldn't work in plastic, so instead the top portion is flat so that a normal woodworking F-clamp can be used to torque it.

Also includes a spacer ring that can be used to uniformly set the pins to the correct depth. 

Due to the steel pins the print needs surprisingly little infill and can transfer quite a lot of force. I printed mine in ABS with 3 walls and 25% infill, and I suspect that a lot less would have been enough.