A few days ago we posted about using soda pop cans as a DIY solder paste stencil. Alistair made a similar stencil about a year ago. He documented the process on his blog, so check it out if you want to try soda pop solder paste stencils yourself.
I described a similar method to this on my blog last year. My preferred etchant is a mix of Phosphoric and Hydrochloric acids. I do toner transfer by printing on magazine paper and using a laminator (10 runs through it to really heat up the aluminium).
Via the comments.