Mine went out today but I have little faith it is correct. I tried to convince the woman at the PO that I wanted to use a First Class mylar envelope but nothing do her but I use one of the cardboard envelopes. I did (I think) succeed in getting her to put postage on it for another ounce.
There is usually another woman that works there that is used to me shipping things out with return envelopes. I specifically went out of my way so I could deal with her and she was off. Bummer!
Anyway, they should be there late this week.
The PO lady told me everything I wanted to do was difficult and expensive. I was shipping a quilt to San Antonio and some fabric to Salt Lake City and these squares. Seemed fairly simple to me!