Two-piece arms for Mad Cat MKII

I was having real trouble printing the original arms for the Mad Cat MKII (http://www.thingiverse.com/thing:44025) without failing. Three consecutive prints failed at exactly the same place; the print head was hitting the print during a non-print move (which there's a lot of due to all the support material). Also, trying to clean out the support material inside the "shield" was near impossible due to the tight spaces.

So, I redesigned the arms to be printed as two parts; a "shaft" and the "