I made lots of thank you cards recently. They are really simple, if you didn't know I like sewing onto paper and card! I also made some envelopes. Here are a few that might help you be inspired!
For the insert I sewed the paper inside rather than glueing - just because I can!
To make the envelopes: fold a large piece of paper (I used wallpaper) around the card. With the card inside and already written, fold the two edges around the card and sew the edges together.
Simple and unique.
Have fun sewing some cards!