Thought I'd share this...
I was wanting a tank for my rat rod beach cruiser project that held enough fuel to go for a decent sunday cruise yet didn't stick out like a sore thumb...I seen an under seat roll up leather tool bag on a vintage bike on another site and well it gave me the idea for an under seat tank. I started out with an apple juice can that holds about 1.5 liters and an old contact cement can that I cut the top off of so as to salvage the spout and cap. I cut a hole in the juice can, carefully shaped it with my dremel, then inserted the contact cement can top and formed a flange after it was in. For the fuel drain side I bent up a length of annealed brass tubing with a tubing bender and then added a flange...now how do we get that sucker in the hole I just drilled?? lol...I ended up cutting a big hole in one end of the can and inserting the tube from the inside. After I got the cap and drain inserted I soldered them both in real well with a pencil torch and some silver bearing metal work solder...and...so far so good...no leaks! I still have to solder the cover over the big hole I made in the end plus figure out some mounting attachments and a cap saver but so far I'm quite happy with the how it's turning out. I have a bag full of leather that I salvaged from an old black leather couch that was sitting beside a dumpster and after I get the fabricating done and give it a coat of paint I plan on wrapping it in leather.
Should look pretty neat when it's completed and mounted under a fat vintage looking springer seat