I bought an Enveloper by Crafter's Companion...thought at the time that it was a bit pricey but just love it. Made some envelopes out of CS and PP I made from Papertrey, also used a SU set. This gadget is very user friendly for making envelopes. The smallest one is ATC size which I thought was cool!
Unfortunately the envy using Posh stamps has a slightly smeared label on it, but I will still use is to put something i the mail...sometimes it is hard to wait for the ink to dry...lol...
Here is a link with further info on this gadget