Igus pad for narrow-slotted 2080 aluminum rails

Remix of Rexipus' Igus pads. The trapezoid block has been narrowed to fit 2080 and 2020 extruded aluminum rails with 6.25 mm slots. Snaps onto Rexipus' x-y Igus filament slider blocks.

I've added a lower friction version with more "speed bars" and a carved out center area.