One of things I remember vividly from my toddler years is having light up trainers (sneakers for Americans) - the ones that flash when you walk. After finally coming to the conclusion that you just can't buy these in adult sizes I resolved to make my own.
For this first attempt I decided that the easiest solution would be to find a pair of light up kids trainers, take them to bits and transfer the lighting system into an pair of adult sized trainers. However, trends must have changed since I was young - there are very few light up trainers available now even for kids. After much searching I found these:
Each shoe has three LEDs in a plastic bubble and an on/off switch. I armed myself with a craft knife and started to remove the lighting system from one of the shoes. This turned out to be a lot easier said than done - the wiring is very fragile and the shoes are full of glue.
The lighting system is very simple. A small sealed circuit board (the control module) houses a motion switch, a button-cell battery and a tiny microchip. The LEDs and switch are all connected to it via extremely thin cable. The module was about 6mm thick and around 2cm square. Contrary to my expectations the LEDs were all individually controlled.
The next step was to transplant the lighting system into some adult trainers. I bought some cheap unbranded trainers to experiment with. When selecting these I made sure to choose trainers with lots of padding, to give myself somewhere to install the control module.
It was fairly easy to install the light system into one of the adult trainers. Using an awl I made three holes for the LEDs, wedged the control module into the padding, tucked all the wiring into place and then neatly finished it off using a fabric mending patch to hold everything in place.
I tested one - it fitted nicely and I couldn't feel the module or the wiring. The lights appeared to work well when I walked. Considering this to be a success I repeated the process for the other trainer. The final result: