Building Blocks Case that can hold a 9v Battery and 5v UBEC for servos or a PCA9685 board. You can stack two blocks ontop of each others with the lid in the middle part.
Extend each end of the case with a controllable leg. This way you can build and connect larger systems, when you have a multiple batteries and PCA boards connected, with one Raspberry Pi you control as much as about 900 servos total.
Download and install the controlling Demo app for your Raspberry Pi here http://gigabrain.io The Demo version has maximum 6 servos to control with 1 PCA9685 board.
You can use these extensions also in Vorpal robot to extend Vorpal legs or other Hexapod Quadruped or Bipedal models.
See also an the hinges here