This will be the first of several parts on electronics for Props and Cosplay. We will use an library containing a collection of LED patterns to make things easier.
Simple Cosplay Lights (using an Adafruit M0 Trinket)
High Brightness 3W LEDs (using Pixie)
Bluetooth (using an Adafruit Bluefruit Feather)
Prop with Light and Sound FX (using Teensy and our own extension board)
While a variety of Arudino compatible development boards can be used for this purpose (and is also compatible with the software we are using). A M0 Trinket is best suited for this purpose. It is powerful, low cost, and takes up minimal space. It is essentially the latest and greatest replacement to older ATTiny based boards.
An 18650 battery will provided a lengthy run time. There are a variety available, one with lead wires makes assembly easy. If the project is space constrained, there are also a number of lithium polymer batteries available.
An Arduino library containing a number of LED patterns, which man be configured for the user to cycle through with the click of a button. Patterns are added over time.