A tool to help assemble the Traxxas 5347 ball joints used in the Delta Steel

Delta printers use joints, there are basically three kinds available right now:

1. Clevis joints. These were used in the original Rostock and also originally used in the Delta-Pi. However apparently they wear and when there is some play in the joints, printing becomes noisy and loses accuracy. Mike Paauwe, the original designer of the Delta-Pi, has recently switched to Traxxas ball joints (see below).
2. Magnetic ball joints. These require - obviously - strong magnets and steel balls. Imho this considerably adds to the weight of the effector and carriages, however, these joints do not wear and there is no play. The main problem here is availability.
3. Mechanical ball joints, such as the Traxxas 5347 originally used for R/C models. These are inexpensive, widely available and weigh very little. Wear is probably tolerable (we'll see how that goes) and there is little to no play (again, we'll see) . These are the ones I will be using for the Delta-Steel prototype.

Now, it must be possible to assemble those Traxxas 5347 ball joints with pliers, but I honestly think I have found a better, simpler, and less damaging way of assembling them:

I designed this little tool in OpenSCAD (source code and .stl file are available on Thingiverse). Then I printed it in less than 30 minutes on my P3Steel.

Now all it takes to assemble one of these Traxxas 5347 ball joints is a firm press on the pusher part of the tool and the ball will snap in place. I assembled all 12 ball joints used in the Delta Steel in less than 5 minutes, and only one of them is showing a little bit of play.