To save as much space as we could, we'll use the short male and female header pins to connect the Feather M0 and Music Maker wing.
To keep the head aligned, we use a bread board and then added small pieces of sticky tac to help hold the Feather in place while soldering.
Solder male headers
Position the long ends of the male headers on the breadboard as shown in the picture. We'll lay the Feather over the pins and then solder the shorter side of the headers to the back of the board.
Check that all of the the pins have enough solder applied to each pin. Now we'll turn the Feather board over so the back side is laying on the breadboard.
Fit the female headers onto the male headers and then lay the Music Maker Feather on top. Apply a small amount tac on the sides of the Music Maker to hold and align the female headers in place.
Solder female header
Carefully solder each female header pin without moving the boards. The enclosure port holes won't properly align if the headers are soldered on crooked.
Check header connections
Remove the tac and check that all of your solder points are connected. Make sure there isn't excess solder bridging other pins.
Gently remove the Music Maker wing and set it a side as we'll move on to soldering the buttons.
Bend buttons legs
Slightly bend the legs outward with a pair of flat pliers. We'll need to gently pull them back far enough to fit through the button mounts inside the enclosure.
We'll need to solder a wire to two of the legs that are diagonally across from each other. Apply a small amount of solder to both legs and then cut wires for each. Cut six wires 57mm long, for each io pin and ground connection needed.
Solder ground pins
First, we'll solder the ground connections to all three buttons along the ground rail on the prototyping are of the Feather M0.
Use a third helping hand to hold a slide switch and tin two pins and then remove the third pin. Don't remove the middle pin. Cut two wires 49mm long and solder them each of the pins on the slide switch.
Turn the Feather M0 over and solder one of the slide switch pins to the EN pin and the other to the GND pin.
Insert slide switch
Insert the slide switch at an angle between the two walls inside the enclosure as shown in the picture. Make sure the port opening for the switch are clean. Use tweezers to help push the switch through the port opening.
Now we can carefully mount the Feather M0 inside the enclosure. Align the port holes and use M2.5x5mm long screws to mount the board.
Insert the buttons at an angle. You can use tweezers to help push the buttons between the walls and into the cut outs for each.
After inserting each button, gently bend the leg back inward to make room for the next button.
Now we can mount the battery on top of the Feather M0. Plug the battery into the JST connection on the boards and then arrange the wires into the corner of the enclosure.
Attach Music Maker Feather
Align and mount the Music Maker Feather on top of the M0. Make sure to maneuver the ground wires so the headers don't kink them when mounting.
Solder button pins
Now we can solder each button to pins 13, 12 and 11.
Gently remove the knob on the potentiometer by carefully wedging your fingernail between it and the base. The printed replacement fits into the white plastic nub.
Solder pins as shown in the circuit diagram. Tin all three pins on the potentiometer, cut three wires 83mm long and then solder to each wire.
Now we can solder each pin to A0, GND and 3V. You can solder wires to the secondary pin or right on top of the header pins to avoid soldering so close to other components on the Music Maker board.
Use a third helping hand to hold the tiny Sequin led in place while tinning a soldering wires for power and ground.
Cut wires 82mm long and solder them to the + and - pads on the sequin.
We can mount the sequin on the corner, over top of the Music Maker wing as shown in the picture.
Orient the potentiometer so the pins are pointing towards the long side of the lid and gently push it inside the port opening walls. Gently bend the pins straight to fit it inside the enclosure.
Align the lid so the potentiometer is over the SD card slot. Press the lid so the snap fit nubs on the side snap fit together.
Attach wearable clip
Next we can go ahead and push the printed clips through the back opening on the enclosure.
Align the two the screws mounts so the back flat side is facing away from the enclosure as shown in the picture.
Align the clip to the slot on the enclosure. Press the protrusion on the clip into the slot until the screw mount pushes up against the back of the enclosure.
Use M2.5x5mm long screws to secure the clips to the enclosure.
Make sure the protrusion has a tight fit into the slot or the clip will have a weak hold when wearing.