M42 to Canon EF / EF-S Lens Adapter

This 3D-printable M42 to Canon EF adapter offers an affordable yet reliable alternative to commercial metal adapters. It can be printed in under 30 minutes on most modern 3D printers.

Originally made for the Helios 44-2.

Parts

For assembly you will need a printed part: (M42 - Canon EF adapter)

Printing Tips

• Use at least 4 perimeters.
• 5 top and bottom layers recommended.
• 25-50% infill works best.

Assembly

No assembly required!
Simply print the adapter, remove the built-in support, and it’s ready to mount your M42 lens and attach to any Canon EF or EF-S camera body.

For better grip during installation, an optional installation tool is included, though it’s usually not needed.

Etc.

Added .step file for anyone to easily remix the body mount to different threads, etc.

2025-10-15 initial release