thanks, Jim, two things:
(1) my way, in the post above, is perfect for cheap, sturdy chips. There is no way the post office could make a fuss as long as the letter is no more than 1/4 inch thick, is normal size envelope (I forget the criteria there), is no more than 4 ounces, and you pay the 17-cent surcharge for the uneven, rigid aspects. If it is un-machinable, they don't bump you up to a higher classification (flats, parcels) -- they just want the mere 17-cents surcharge.
(2) I never had anything returned or had a postage due problem. This is funny, crazy -- once I took a priority mail post office box that I received in the mail (had canceled postage on it, of course), and I did some cutting and turned the cardboard box inside out, and used it to mail something. Here is the crazy part -- the post office people opened it, saw it was a priority mail box, so they repackaged it and charged the recipient the difference for priority mail! Not very "green" conservationist of them, eh? (They don't want you to use the priority mail boxes for regular mail, but a used box.......?)

Robert