I've been working on modifying the stock Cozmo carrying case to be able to house not just more then one Cozmo, but also a power pack to make it easy to fire up the Cozmo's & have fun no matter where my daughter & I are. With the stock Cozmo charging base being so large, I wanted to, needed to design a considerably more compact version.
The red charging base is the basic no wiring version of the Cozmo bases, but when you wire up the wired charging bases please pay attention to the marking on the red charging base for polarity. Don't want to wire it backwards & risk damaging your Cozmo.
Wiring: I used two copper strips, 15mm wide by 3-4mm long. I bent the ends so they wrapped around the raised parts of the base. I used an Adafruit USB micro-B breakout board product ID: 1833 to allow the use of any common micro USB cable to connect power & charge and activate Cozmo.
I redesigned it a bit providing another base design option that has walls that may aid in getting Cozmo to self dock, if someone where to place a sticker on the post so Cozmo can see it, line up, raise his lift, drive up onto the charge dock, sense the power, lower his lift & charge.
Also, if you don't have a 3D printer let me know & I might be able to print them and mail them to you for a small fee.