Raspberry Pi Sleeve with Ballast Pockets

A remix of dktosoch's raspberry pi sleeve that adds ballast pockets. I intend to use lead shot to give the case some heft so it's not flopping around when you plug a couple cables in.

The idea is to pause the print before the pockets are sealed.

Note that I have not yet been able to print this, I'm trying to solve some issues with Cura 3 removing the internal geometry in the print.