Here’s an example of what can be done with the strapOn protoboard platform. I’ve taken the tinyEMF circuit, saved some space (by using smaller rectangular LEDs that I filed down and replacing individual resistors with a 9-pin resistor bus), and rebuilt it on the protoboard so it’s easy and lightweight to wear.
It’s currently powered by a 3.7V lithium battery cell I found in my parts bin.
Long-term plans for this include adding several sensors/peripherals (e.g., RTC, temp/humidity/barometric pressure, light level, etc.) with a common i2c bus, and possibly a lithium charging controller. About 2/3rds protoboard, and 1/3 SMD peripherals is the eventual goal, allowing anyone to add whatever microcontroller they would like, while accessing several hardware features with a common i2c bus.
More on this later–this post is really only intended to show what can be done with the strapOn board and a couple of hours of tinkering.