Solder pin headers to the Feather M4 Express and the Music Maker FeatherWing. Additionally, solder the MIDI jumper closed on the back of the Music Maker FeatherWing. This puts the Music Maker FeatherWing into MIDI mode as described in the product guide.

Solder socket headers to the FeatherWing Doubler. You can use the Feather M4 Express and Music Maker FeatherWing as a soldering jig to keep the headers aligned. 

Place the FeatherWing Doubler on the 3D printed acrylic support. It will eventually be mounted there.

Solder the lasers' ground and power from the switch to the FeatherWing Doubler.

Cut, splice and tin two pieces of wire that are approximately 210 mm in length.

Solder one wire to 3.3V and one wire to ground on the FeatherWing Doubler.

Cut, splice and tin two pieces of wire that are approximately 191 mm in length.

Solder one wire to SDA on the FeatherWing Doubler and one wire to SCL on the FeatherWing Doubler.

Solder these wires to the TCA9548A:

• Doubler 3.3V to VIN
• Doubler GND to GND
• Doubler SCL to SCL
• Doubler SDA to SDA

Cut, splice and tin two pieces of wire that are approximately 165 mm in length.

Slip a piece of heat shrink onto the STEMMA ground and power wires. Solder one of the 165 mm long pieces of wire to STEMMA ground. Solder the second 165 mm piece of wire to STEMMA power.

Solder the STEMMA power wires to the FeatherWing Doubler.

• STEMMA ground to GND
• STEMMA power to 3.3V

Apply the heat shrink to the STEMMA power wires.

Mount the FeatherWing Doubler to the 3D printed stand using M2.5 screws and stand-offs.

Mount the TCA9548A to the center mounting holes on the acrylic using M2.5 screws and stand-offs.