Demo device printed with NinjaFlex and Black Magic 3D Conductive Flexible TPU Filament. It uses one CR2032 battery to power the LED via trace made out of conductive TPU.
See video: https://youtu.be/6Q8_tnLKeCs.
The red LED is melted in place by heating the pins with a soldering iron. This connection is more stable than just punching the pins through the conductive TPU.
20% for NinjaFlex 100% for Conductive TPU
The printer was upgraded with a Flexion Extruder (https://flexionextruder.com)
15/09/2017 - Figured out I uploaded the wrong design. Uploaded new STLs, now the two parts fit together.