Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:3976851.

Simple, can be bolted to End of extrusion but you need to tap. M5 Bolt Hole. Keeps the 6mm belt from rubbing the extrusion. Meant to work with 20t 2gt belt pulleys, not the flange bearings. Print the Cap at 0.2 with curved part facing down. Print the bolt at 0.12 as shown in pic. It works well enough for what this is.

V3, updated to allow more side to side offset of belt without allowing it to hit the 2020 still.