This is the bumper for the proton pack build. I had to split it into three parts for my printers bed. Mounted with screws and glued together, it should be strong enough.. Each part will fit on a common 200x200 bed.
Update: Properly voided slots for the joiner on the three main parts. This should give good mechanical strength and alignment once glued. Also reduced the joiner in dimensions a few tenths of a millimeter so they would fit in the holes! (ha!)
Update 2: There's some ghost data in the middle part. Even netfabb couldn't see it. However, each slicer I tried wanted to print a weird rectangular shape on the first layer. I finally used Cura, which allowed me to discard the first .5mm of the print before exporting the G-code. I've loaded the part in blender, and looked, but there's nothing there, so I guess the ghostbusters might actually be needed for a real fix. Meantime, use Cura to slice it and drop the first .5mm.
Update 3: Be careful with the side that has the overhang all the way around. Slic3r put one strip of 2mm fill in that overhang and my printer almost ate itself trying to move the bed back and forth REALLY fast on that strip. I got through it by slowing the printer to 40% during that overhang. I don't know if other slicing software will put that 2mm strip in or not, you have been warned.
There are four pieces. The left, right, and middle parts of the bumper, and a small rectangular tab that joins two pieces as a guide for gluing. I'm not sure if 5 minute epoxy eats PLA or ABS, but if not, use that for strength.