In the original design I wanted to use a custom made optical encoder. I decided to spin my own board for this and figured I might as well integrate regulators and a PWM chip to drive the servos. Below is the board layout. On the side back side in blue are the infrared photodiodes that I originally planned to use as an optical encoder through the rotating barrel. There are 8 Servo connection at the top that drive the motors. There are two regulators: one that powers the servos and one that powers the Raspberry Pi. The regulators can be enabled/disabled to shutdown the Pi and save power. They are separated to avoid brownout on the Pi's supply when multiple motors are consuming a lot of power.

Here's the parts list:

• 5 RR1206 IR photo diodes
• 2 MCP1826 5V regulators
• 1 PCA9685 PWM IC
• 2 4.7 uF caps
• 1 10uF cap
• 2 1uF caps
• 5 10k pots
• 8 220-ohm resistors
• 3 10k resistors
• Male headers

Here's the associated schematic: