Geday, I've remixed this part again to now accomodate the new rod spacing on the PLUS 2.1. This part tends to hold the rods a lot firmer than the original wooden parts. When using the 2.1 rod spacing, do not use the middle screws, it's so firm you don't really need them anyway.
I've just updated this for better rod spacing that should correspond correctly to the printrbot PLUS 2.1. It also means you can now use the middle holes.
I also removed the nice edging on the top surface just to simplify and speed up printing.
Keep an eye out for my 2.0 to 2.1 conversion kit!