Before starting it's a good idea to get your tools and workspace suitated. You'll want to have wires, tools and solder close by while you work through the sections.
The wiring portion of this build is split into sections relative to the components. This hopefully makes it a good way to take breaks when completing sections.
The slide switch is wired to the Powerboost 1000c with just three wires (Vs, GND and EN). It's wired to the enable pin so that it safely discharges the powerboost 1000c. This however will not safely power off the Raspberry Pi - You'll still need to "sudo -halt p" that to do that safely.
The Raspberry Pi, PiTFT and PAM8302 are powered by the Powerboost 1000c and a 2000mAh lithium polymer battery. A Pi ribbon cable connects from the PiTFT to the positive and negative power pins on the powerboost breakout board (in place of the USB port). The microUSB port on the powerboost can be used to recharge the lipo battery. The lipo battery connects to the on-board JST conenctor.
This 2.5w mono amplifier is powered by the powerboost 1000c (5V and G). The audio input is connected to the audio jack pins on the bottom of the Raspberry Pi. A single mini metal speaker is wired to the output on the breakout.
The PiTFT is designed to fit ontop of the Raspberry Pi GPIO header. The PCB on the display has a GPIO socket which can connect to a Pi ribbon cable. We'll use the Pi ribbon cable to wire up tactile buttons for the controls. The 2.4' PiTFT has five spots on the PCB for tactile buttons. Use these buttons as pause, start, L shoulder, R shoulder or even exit ROM. The display shares power with the Raspberry Pi, so that gets powered on when the Pi ribbon cable is wired up to the powerboost 1000c.
To connect our buttons we're using a perma-proto half-sized breadboard to contain them together on a PCB. The PCB will need to be cut and trimmed to fit inside the enclosure. The 6 controller buttons are soldered to the PCB. The Pi ribbon cable is wired to these buttons. The perma-proto has a power rail, so we can connect the ground together in series.