Add 2-3 layers of gaffer tape around the outside of this tool so it has a sliding fit in the axle tube (no radial play). Without the tape, the fit is loose and it will not press on the seal evenly.
When the seal is fully installed, the back of this tool will be nearly flush with the end of the axle tube.
Print it so the raised lip is facing up.
The author marked this model as their own original creation.