Summary

Use this simple mask to apply Kapton tape to you HBP.

This made be the simplest design ever on thingiverse but damn if its not helpful.

Instructions

Cut it out of what ever you have laying around. I like wood because the tape is easier to move around to get it in position. Don't use anything over 1/4 or 6mm thick or it could make it harder to place with clearance in the back.

There are two indents on the cutout that mark where the centerline is.
So you can apply your Kapton tape to the applicator and move it around till it is stretched over the frame. Then place the back down over the connector and use your squeegee to press it down towards the front. This is helpful considering that the space inside the replicator is cramped to work in and that the tape is always moving around as you try to apply it freehanded.

Replicator Kapton Tape Applicator