Drop in T-Nut for 2020 V-Slot rails so you do not have to take things apart to attach new things.
You will need to print this with 100% infill and do a fair amount of clean up on the part. The STL file may need to be inverted on X. I designed this on my printer and am starting to think my X is going the wrong way.
Also the hole will need to be drilled and tapped. I have tapped these with up to an M5 hole and gotten them to hold however I would recommend M3. Also keep in mind this is plastic so it is easy to strip the threads.
EDIT: Yep X was inverted. I just uploaded an X inverted version of the file.