Attach three M2.5 stand-offs with M2.5 nuts in three of the Feather nRF52840's mounting holes. The mounting hole at the back of the board next to the headers should remain empty.

Attach the Feather nRF52840 to the mounting bracket using three M2.5 screws.

Plug the rotary encoder into the Feather nRF52840's headers. The rotary encoder breakout board's mounting holes should line-up with the mounting bracket's mounting holes.

Attach the case's lid to the mounting bracket with four M2.5 screws. The screws will go through the mounting holes on the lid, rotary encoder breakout board and the mounting bracket.

Secure the lid to the mounting bracket with four M2.5 nuts.

Plug a LiPo battery into the Feather nRF52840.

Insert the mode switch into the cut-out on the side of the case.

Insert the on/off switch into the cut-out on the bottom of the case.

Close the case with the lid and you're ready to use your new BLE remote!