I'd been kicking around the idea of a cheap stylus-based synthesizer project for awhile, and after my great success with the Blinky 8-bit Tiara and Earring set project for MAGwest 2017, they were hip to let me do whatever project I wanted, and so I got approval to start design on a synthesizer project. The budget is supposed to be $20 a unit or less (same as the tiaras). I started on it before I even left the convention site of the 2017 MAGwest show.

At the time I was pretty keen on the Arduino environment, because my experience using it to develop using the Teensy microcontrollers, but at $20 each those were too expensive to put in a project with a complete project of $20. I discovered that STM32 "Blue Pill" boards were available from Aliexpress for less than $2, and having a 32 bit processor at 72Mhz and a ton of I/O lines seemed like a pretty good solution.

I decided to try to use as many off-the-shelf components as possible so that I could just solder them together myself if necessary.  At the time, I hadn't ever manufactured anything in China other than bare PCBs, and wasn't really sure about the idea of sending the whole project out. You can get a lot of "maker parts" cloned off the open-source hardware designs that Adafruit and Sparkfun release for much cheaper from Aliexpress, which would enable me to get just about everything I need for ~$10.

It sounds like a plan!