After making a few holes in my belts, I created a small belt holder that can be used instead of a tnut and a screw.
Included are the Sketchup source and the generated STLs files. Every printer is calibrated differently. When printing these holders, make sure you get a snug fit, if these are made snug enough, they don't even need to be screwed in place. Print test holders and play with the scaling option to ensure you have a tight fit. I've been running my machine without the holding screws, and the belt and the holder are still in place.
VSlot Belt Holder 1.0
This holder allows for holding a belt without the need for screws or a T-Nut