Get an openSip+Puff PCB
PCBs and assembled boards will be made available once prototyping is finished and I can find some way to raise the capital needed. For now you can get boards made through OSHPark using the Eagle files supplied, but please contact me beforehand to confirm that the uploaded design is solid.

Order all the components from the Bill of Materials
I get all of my parts from Digikey, but you are free to get them from anywhere. The ATmega32u4 and the pressure sensor are the most expensive parts of the project, and you can expect the total cost to be around $20.

Assemble the board by soldering all parts
Be careful, be safe and be aware of all polarity and registration markings. A reflow oven may be helpful here, but I solder all the boards by hand using a standard soldering iron for now.

Burn the Arduino Leonardo bootloader onto the ATmega32u4
Using the ICSP headers supplied on the board, burn the bootloader onto the chip. This can be done using the Arduino IDE and an ICSP programmer such as the USBtinyISP.

Upload the firmware sketch provided onto the board
Get the latest firmware sketch attached to this project or via Github and upload it using the Arduino IDE. Or create your own and share!