Angled MK3 Heatbed Cover with Nylon Filament Hole

I made a few small amendments to the already great design by MIKEYMCC for my MK3.
- Added a support hole for the 3mm Nylon Filament included with my kit to keep the wires in shape
- Reduced the top piece height by a little more than 1mm to make it more low profile
- Moved the Nut pockets to the bottom half so its easier to install and remove

NOTE: This only works for the original MK3 SOLDERED bed terminals. The screw terminals on the newer beds will not fit.