It's another favourite project from my 5 years as a Stampin' Up! demo today.
This is one of the self-closing boxes that I came up. Yes, this was my invention, which came about when I was following instructions to make a stand-up pouch and suddenly realised that I could do something different with it...and this shape was born!
Here's how I made this version (with special appearance by a certain cat...)
This box can easily be adjusted to any size. I've made a calculator that will allow you to make a box of any size (subject to the size of your base card!) and works in inches and millimetres. You can get it from my Google class -
classoom.google.com and join with the code jhab6d
(This is an updated version of the calculator - the previous version had an error, so if you've downloaded it before, please get the new and improved version.)