Portable Makey Makey indicator lights.
Step 1: Components
Portable battery pack as power source.
Conductive thread and metal haberdashery buttons.
Male-Male jumper wires.
Step 2: Wiring prototype.
The Makey Makey v.1.2 has 2 outputs (one keyboard, one mouse) and it is through these we drive the LEDs (one RED for Port, or Left; One GREEN for Starboard, or right).
These through-hole diodes are useful in prototyping, but you'd need surface mount LEDs to sew on a garment shoulder/sleeve to use as actual turn indicators!
By pressing on a metal button sewn onto a cuff/sleeve with conductive thread, and running lengths of conductive thread inside the garment back to the board (the Makey Makey) we can actuate the light, or even press both simultaneously and have both LEDs light up to indicate sudden breaking in large crowds :D