Accessory mount (26mm) for 50mm bike tube frame (e.g. recumbent)

This is a clamp to mount devices meant for a regular European bike on a 50mm tube-shaped bike frame. You will need a rubber O-ring with a diameter of about 40-45mm to attach it firmly. I also recommend a few tiny drops of hot glue or a thin sheet of rubber when attaching it, to prevent rattling.
The design also features two small cable guides at the left side.