This is an optimized version of the Festool Systainer mounting rail. I took measurements from the original author's Fusion360 file, but rebuilt to fix their original design error and optimize the design for quicker 3D printing.

This rail fixes the original issue with the central guide being too long. It is also thinner than the original design while retaining the same features and mechanical properties. It's also shorter by approx. 40mm which makes it almost the same depth as a standard Systainer M container. This rail can be printed diagonally with 5mm brim as a single part on a BambuLab X1.

I recommend printing from ASA/ABS or at least PETG for good mechanical properties.

WARNING
Because of the change in thickness you will not be able to use these in the same width cabinet as the OEM rails without shims.