I have built one myself and a squaring rig all in one, I bought a G5 tool for nothing !
I use a dremel to cut the shaft which I rotate onto an L shaped aluminium bar.
there's some pics of it here;
http://www.flickr.com/photos/69041177@N00/sets/72157601234372217/

to square the arrows I just put a sharpeningstone at the cut off end and spin the arrow a few times.....
the whole thing cost me about 35 dollars.....

Frank
Belgium