I've hit a bit of a slump with this project so I'm writing a log to try and clarify my thoughts.
I like to think that I'm not the only maker whose shelves are littered with half-finished projects. Initial ideas are exciting, and that excitement often propels me as far as an initial proof-of-concept build, but then the grind of iterating the design kicks in and that often causes me to give up. "DrumKid" has already surpassed the vast majority of my previous projects, in that I've created several breadboard versions, a stripboard version, and two PCB versions, as well as a 3D-printed case. This is something to be proud of, and yet, paying-the-bills work has pushed DrumKid development off my immediate list of priorities, and the Hackaday Prize deadline is steadily moving closer. What to do?
At the start of this project, I promised myself I would take the simplest route where possible. Getting bogged down with power management, amplification, and case design has taken me away from the super-simple design I was imagining. It's time to be brutal and come up with a simple, bare-bones product. My mentoring session gave me some really good tips about how to simplify the circuit design, and now I think I have a good plan for simplifying the case design - by not building one.
A friend bought me a Pocket Operator drum machine for Christmas. This instrument is made by Teenage Engineering, who seem to specialise in stripped-down design. The Pocket Operator is simply a single PCB, with buttons, knobs, and a display on the front, and batteries on the back. All the other components appear to be hidden under the display.
If I can design DrumKid in a similar way, I think that would solve a lot of my problems. Since I'm using fairly chunky through-hole components, I might need to use two PCBs (separated by stand-offs), one for the interactive components (buttons, knobs, LEDs) and one for the "other stuff". I might also need some sort of covering to prevent fingers touching sensitive circuitry.
I like the aesthetic of the Pocket Operator, too - it's simple and utilitarian, but playful at the same time. I'm going to do a few sketches and see how practical it is to make a DrumKid prototype in a similar style.