We'll start the assembly with the Adafruit Feather. The Feather will be mounted to the bottom half of the enclosure. Position the Feather PCB over the center of the case. Lay the board over the standoffs and line up the mounted holes. The microUSB port from the Feather should be facing the edge of the case.
We'll use 2x M2.5 (4mm long) screws to secure the Feather board to the bottom halve of the case. While holding the Feather PCB down, insert a machine screw into one of the mount holes and fasten it until fully tightened. Repeat for the second mounting hole.
Next component we'll mount to the bottom half of the case is the PCB from the thumb joystick. Position it to the left of the feather board (positioned down, in the photo) and line up the mounting holes with the standoffs. Adjust the wires so they're not being kinked. You may need to snip any excess pins from the bottom of the PCB to prevent the wires from being punctured.
We'll need 4x M3 (4mm long) screws to secure the PCB to the case. While holding the PCB in place, insert and fasten the machine screws. The orientation of the board matters, so make sure to cross reference the image.
Install Screws to Button PCB
Moving onto the button PCB, we'll need 4x M2.5 (4mm long). I suggest installing the screws into the button PCB first, going through the copper side. Fasten them to the four mount holes until the threads just barely poke through the other side. Repeat this process for the four screws.
Install Button PCB
Grab the top half of the case and position the button PCB over the standoffs on the right side pad. Adjust the PCB until the screw threads fit over the mounting holes in the standoffs. The orientation doesn't matter all that much, as long as the wiring is long enough reach.
Secure Button PCB
While holding the button PCB to the standoffs, fasten the machine screws until fully tightened. The surface of the PCB should be flush with the top edge of the standoffs. Test the button actuators by pressing them. They should have a bit of travel and be sticky free.
Install TFT Display
Next, install the display to the top half of the case by resting over the four standoffs in the center. Orient the PCB so the wiring is near the bottom and the SD card facing the other edge. You may need to press down on the PCB so the bezel of the display fits in between the standoffs. The tabs on the PCB should sit flush with the standoffs.
Secure TFT Display
Insert four M2.5 (4mm long) screws into the tabs of the PCB with the mounting holes. Fasten the screws until they're fully tightened.
The slide switch can be inserted into the little holder near the Adafruit Feather. You'll need to insert it at an angle and press it down until it clicks into place. A little nub will keep the switch from being pushed inside the case when actuated.
I used a glob of mounting putty (tack) to secure the battery to the bottom half of the case. This stuff is nice because it'll keep the battery from rattling inside the case but is also removable/adjustable unlike tape or glue.
The battery fits nicely next to the Adafruit Feather. Adjust the position of the battery so the cable can reach the JST connector on the Adafruit Feather. Once in place, plugin the JST connector from the battery.
With all of the components now secured to the case, double check all of the mounting holes and ensure everything is tight and none of the wires are being kinked. At this point, it's a good idea to make any final adjustments. A good example would be to shortened any excessive wires. Long wires are OK, but they may prevent the case from being able to fully close shut.
Close It Shut!
OK, now it's time to close up the case by joining the two halves together. Slowly bring the top half of the case to the bottom half. Make sure none of the wires are bing kinked, ensure all of the connections are fitted inside the case. The two halves will click together and snap fit shut.
Test it, Use it, Play it!
Try it out and see if the screen powers on – The Feather takes about 2-3 seconds to boot, so it's normal if it doesn't instantly powers on. Rotating the joystick should move Joy's pupils. If you notice the movement of the joystick is Inverted, you may have the joystick PCB installed backwards.