FELLOW FELLOW ROCKS! for the original post on her envelopes...
All you need is: paper (whatever colours you like), glue, scissors, and a paint pen (also in whatever colour you like!). I created an envelope template that you can download right here in Letter and A4 formats, so you can print it straight onto your paper! The finished envelope is 8 x 12cm (approx. 3 x 4.7 inches).
Step 1: Cut the paper using the template (or create your own size/shape and draw it onto the paper).
Step 2: I found it easier to fold and glue the envelope before drawing on it so the pattern was seamless, but you can do it either way. Fold along the dotted lines. Glue the centre-back seam, and then glue the bottom flap over the top. Put it under a book for a few minutes to keep it flat.
Step 3: Get drawing! Use your paint pen to draw whatever you like onto your envelopes (this could be a fun task if you have kids too, and would result in some really personal gift packaging!). And you’re done! Stuff it with whatever you like, seal the top and ta-daaaa! :)