I did a post a little while ago about how poor my experience with a "make a stamp at home system" was and poked around on the internet for another solution. Apparently some folks had this brilliant idea to get a 2mm plastic square 3D printed from Shapeways with their designs in the grooves. Then what you do is take something that will dry or cure in a flexible way (like Suguru or Sculpey Bendy) and push it into the grooves. You've basically made a stamp!
I'll let you know how this goes and post my own little tutorial/experience with it.