Locking ball and socket arm - Print and Assembly Optimized

All credit goes to alexrich82 for the original design, I've only done small tweaks to make it easier to print without supports and easier to assemble using either metric 10 and 20 wrenches or included printable versions. I'll design more end pieces to hold various useful things like magnifying glasses etc on an ongoing basis as I make them. I'll also add some other bits and bobs, compatible with "PCB Workstation with Articulated Arms" http://www.thingiverse.com/thing:801279 I love that design but the arms are very floppy, these arms are a nice upgrade to make them stay where you put them instead of sagging over time. I'll adapt the end pieces of thing to use the locking rings soon.