Original designed for my daughter as part of her world book day costume.  This mechanical heart features a number of working gears that all mesh together and can be seen to be working as they protrude from various points, and through the small window.

The back piece of the heart features slots to fit 1" webbing which will allow you to attach a harness should you want to wear it.

Internal lighting is provided by leds, I have included an internal photo of how I added this in should you want to do something similar.