Mechanical Heart

First, paint the glass or glass holder black.

I used acrylic spray paint, but you can also use tempera paint.

The important thing is to apply an even layer.

Assemble the rotary tool and secure the glass.

Level it.

Center the glass with the engraving area using the preview.

Complete the work.

Once finished, clean the object with solvent if you used acrylic paint, or with plenty of water if you used tempera.