I have not tested this extrusion profile in real life, but I have checked it virtually mocked up. They can be printed and should be compatible with Makerslide/Open Rail components. All holes are 3mm in diameter. Feel free to let me know how bad it is, as this is my first attempt at modeling something. I will update this when I get some printed out. And with future updates/accessories.
Test Print the 20mm length test beam.
Update: Took a couple models down due to issues. Will update when resolved.