Battery pack, make you own using Litium Ion 18650 (about 4-6 batteries), with integrated charger (etched by you, can be laser painted) , for printrbot simple 3D printer, or even for any other printer, with ease of connectivity to them... with base case for enclosing the pack and making the top of the base for the printer to have a leveled surface, with some sort of easy release from it...