Well the original muffler broke off a while back and just a pipe was too loud so...
I used two pear cans, crimped one of them and pressed them together for the outside part.
For the pipe I used a 12" long 1/2" water pipe, (which threads right in to the engine) and drilled 5 rows of 7/32" holes in it. I cut a hole just under 1" in each end of the cans, and packed them full of fiberglass.
Finished size: 12" by 3" and the can is 6.5" total.
P.S. I would like to use this as my second project for the contest.