This project was done for the UK charity Remap.
The goal was to give a blind man a device to help him tell the colour* of an LED.
I added a fibre optic cable to a cheap smartphone case, allowing the phones camera to act as the colour sensor. Modern smartphones have lots of good accessibility features that can read out what's on the screen. Overall this project went smoothly and seems to work quite well, although sometimes it can take a little while for the camera to settle down and give a good reading.
It is fairly easy to get hold of cheap phone cases and fibre optic cables, so as long as you have a smart phone available this can be a nice cheap project.
*I'm Brittish so colour not color, but went with color in the title as it will probably get more hits.
Step 1: Building
The fibre optic is a cheap TOSLINK audio optical cable.
I used polymorph (low temperature mouldable plastic) to stick the fibre to the phone but I think Sugru would have been good as well. To get the polymorph to stick well I put a few holes in the case to give a kind of rivet like joint.
A few key things to consider:
Don't bend the cable too tightly or you could damage it.
I was able to use a bit of the spare cable covering to fit over the cable tip to make it softer/seal better against a surface.
You have to carefully line the fibre up with the camera but be careful not to scratch it.
You need to get a good seal around the camera to prevent other light getting to it.
Try to make sure the phone will still lay on a table nicely.