I came across this the other day and thought it was cool. I've used it and the notching came out perfect. It's a tube notching tool, for those of us that cannot afford expensive equipment. You may have to play with the print settings a little, but when done correctly the cut piece of paper should fit exactly on the tube, trace it, cut or grind it, and your tubing will match up exactly. Does different size tubing and angles and it's free.

Here's the link.
http://metalgeek.com/static/cope.pcgi