20mm T-Slot Rail Cover (6mm channel)

thingiverse

This thing was created using Tinkercad, and you can edit it online at https://www.tinkercad.com/things/dtUdw5KjyO1. It's 100% my original design, which is worth something, I suppose. Import this into Tinkercad and adjust the length to your liking. 150mm seemed like a good starting point, but you can make it whatever size suits you best. Since there's no infill, you can cut it with a razor blade without any issues. This custom rail cover fits snugly, even compared to store-bought versions. I use this design to conceal unsightly wires, but its versatility makes it suitable for other purposes as well.