If you are having trouble finding the right sized envelope or dont have the time or inclination to go and buy one, the good news is they are super easy to make with just about any type of paper you want to use.

They also give a great home made touch.  This template illustrates how to cut out the shape of your envelope, just make sure the centre is a little bigger than your card.  Then all you need are scissors and glue!

 

171mm x 120mm envelope