Making brass tailpiece- how thick should the brass be?

I want to try my hand at making some simple brass tailpieces for open-backed banjos, but I'm unsure how thick the brass sheet should be that I use.  I can't find a local brass supplier so I will need to mail order it sight unseen.  For those of you who have made brass tailpieces - what thickness brass do you typically use for nylgut string banjos, and for steel string banjos?

Thanks!