Great little tutorial. Many thanks for taking the time to write it. Theyd be beautiful items.
I think if I took the time to make one of these Id put it in a protective (see though) cover mind. And at least that way you could stick the stamps on it, and a sent from address in the event of a non delivery return.
Mail art is really fun and arrives in much better condition than you would think! Even internationally, and even using evenweave or linen. I always used Aida for mine, though, because its stiffer and I felt it would hold up better.