The last time i did a tunnel was for Chris at Limey Bikes . It was a pain in the ass to do cause I opted to do it the old fashioned way and bend the metal by hand over a piece of rigid conduit. Yeah that sucked!
This time around I saw this write up on Chop Cult and used it to my benefit.
"Narrowing a Gas Tank with Special 79"http://www.chopcult.com/news/articles/six-pack-narrowing-a-gas-tank-with-special-79.html?comment_id=5249
The whole segment is really awesome and I used almost all of it as a step by step to split,narrow and tunnel this tank. Big shout out to Jay Roche from Special 79 for taking the time to show us the step by step on how to do this ourselves.
Here's a few pics of the tool and the finished tunnel.