Solder wires to the center and left leads on the slide switch. Cover the leads with heatshrink.

Solder socket headers to the FeatherWing Doubler. Then, solder the center lead wire to the EN pin on the FeatherWing Doubler. Solder the left lead to the GND pin on the FeatherWing Doubler. 

Solder plug headers to the Feather ESP32-S3 TFT and the USB Host FeatherWing.

Insert the battery into the case lid.

Attach the FeatherWing Doubler to the battery lid mounting holes with M2.5 screws.

Cover the battery with the battery lid. Route the battery cable thru the cutout in the lid.

Plug the Feather ESP32-S3 TFT and USB Host FeatherWing into the FeatherWing Doubler. Run the slide switch wires so that the switch is opposite the USB ports on the boards.

Place the slide switch into the slide switch mount. Plug the battery into the Feather JST battery port.

Attach the slide switch mount to the case with M3 screws and nuts. 

Close up the case, making sure to have the USB ports on the Feather and FeatherWing flush with their cutouts.