Square Head Driver Set

This set includes various sizes of attachable square head drivers with internal squares in the following dimensions:

- 5 × 5 mm
- 6 × 6 mm
- 7 × 7 mm
- 7.5 × 7.5 mm
- 8 × 8 mm

…

By uniformly scaling the model, all desired sizes can be printed.

These keys are commonly used for opening inspection doors on chimneys or bleeding radiators. In my case, the 5 × 5 mm key is for the radiator valve and the 7.5 × 7.5 mm key for the chimney access door.