Edit: For the end cap a flexible Material like TPU is much better. I have also added a second follower body with a flat bottom instead the V-shaped one on request. Edit2: On request I have added another battery insert with thicker walls. But I can't test it right now. Maybe this enables the people who can't print the insert to print one now and hopefully the batteries still fit.

This is a lighted plug follower, which allows you to see what you do when you repin a standard lock with a 1/2 inch (12.7mm) core. It also has the V-grooved front for aligning the pins nicely. Additional parts needed: -white (suggested) or any other color 5mm LED with long legs (there are LEDs with very shorter, they won't work) -2x AG5 batteries Additional tools needed: -small pliers -small cutters -small screwdriver Parts are designed to fit tightly. Print them in white PLA+ or transparent PLA in 0.15mm layer hight. Have fun craftig :).