Arduino Lilypad

The LilyPad is built for clothing. Its round board has large petal-shaped pads you sew through with conductive thread instead of soldering wires, and the whole assembly is designed to survive being washed once the battery is removed. It runs an ATmega328 at 8 MHz on 3.3V, which is slower than an Uno but far kinder to a small coin cell or LiPo. Note that it has no USB port: you programme it through a separate FTDI or USB-to-serial adapter, sold separately. Sewable pads for conductive thread, no soldering needed; Flat profile sits comfortably against fabric; Runs on 3.3V for long battery life; Washable once the power source is removed.