Capped Y-Corners for Prusa i3 - fully parametrized

I have two nice 9mm smooth rods salvaged from old Epson printers and I would like to use them for my new boxed-frame Prusa i3 (using my DIY [brass nut bushings](http://www.thingiverse.com/thing:238490)). So I was searching for suitable Y-corners. Instead of the zip-tied originals, I prefer the capped type, like the one published by [ch1t0](http://www.thingiverse.com/thing:76660). But unfortunately, those are only provided as STL files, so they are not easily reconfigurable.



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