This rail allows the easy production of hollow beads!
Video tutorial: https://youtu.be/-CC-hOdWowM
Tutorial as PDF (in German language, English version follows):
The forms have the following dimensions:
1) 34mm wide and 18mm deep
2) 28mm wide and 17mm deep
3) 24mm wide and 15mm deep
4) 20mm wide and 11mm deep.
Rails are 100mm long
Material - graphite
Dimensions (LxWxH): 100x30x40mm