For a birthday present I made this little napkin fold card. And although it looks a bit difficult, it is very easy to make. The only thing you need is a square of cardstock and your hands to fold the edges. Finally some embellishments put the finishing touches to the card.

unfolded

opening

removed closure

closed

Want to know, how to fold this? Here are some inspiring videos, describing how to do it:
Greeting card with Napkin fold by Sammyfim (German)
Napkin fold card with Dawn (English)