Two-way Cover for Picocalc by Clockwork Pi

This is a snug-fitting cover for the picocalc that can cover the screen and keys when not in use, or be snapped into place  in reverse, like a graphing calculator. Someone had already designed a cover for this thing, but it didn't snap into place on the back when using the device. I find myself primarily using the picocalc outside of my house (buses, planes, waiting for stuff, etc) and I'd rather not have to set down the cover.

No supports required.