I created this part due to the fact that there was gap at the top of the printer in the sheet metal corners. I dropped a screw down there once and that had bothered me. These may help to keep the heated air in the printer as well, I haven't tested the theory but it is sound since I have held my hand over the corners while printing ABS and a decent amount of heat was escaping from those locations. They could provide extra frame strength as well, but I'm not sure if it's needed.
The normal piece is for the two front corners and back left corner
The piece with a section cutout is for the back right as the bearing mount was in the way for the original piece on my machine
Printed in ABS with 3 shell layers, 7 top and bottom layers. My infill for these parts was 30% and layer height 0.12mm, feel free to change them to your desired amounts.
Parts are press fit into the frame corner holes.