A simple box and cover I 3D printed to keep cables tidy and gives a place to mount the Arduino Mega and Raspberry Pi 3.
I designed a battery holder for a 12v/7.0 amp recharable lead acid battery (a bit overkill). The holder also includes a mount for a power switch.
I modified an existing mecanum wheel design to use parts you can find at a local hardware store.
The nice thing about these mecanum wheel are that they are entirely 3d printed apart from the 4-40 threaded rod and lock nuts to secure the rollers. The sections of rod are cut to be about 2.5 inches.