Full credit to pronoob024 for the initial file and for the idea.

I would highly recommend checking out his video here:

https://youtu.be/TEUXXG1_aYY

1. 3D print the jig in PLA.
2. First, drill into the axle using a 3.5 mm drill bit.
3. Then, use a 4 mm drill bit to widen the hole you created.
4. You can now use VEX screws to attach the shaft to other parts.

• Changed the hole sizes to 3.5 mm and 4 mm as these worked best for us.
• Added text labels to mark the 3.5 mm and 4 mm holes.