You can download my design from Thingiverse.
I used this Poweradd USB 5000mah power bank from Amazon, it was $11.99 and free shipping with Amazon Prime.
There are 2 coffins to 3D Print, an inside and outside shell that slide into each other(see the video below).
Black 1/8" acrylic
Autodesk Fusion 360
Adobe Illustrator