What are the options for building custom sensors, and how might I go about doing it. For FTC.

You could try the HiTechnic experimenter's kit:

http://www.hitechnic.com/cgi-bin/commer ... ey=SPA2017

I don't really know about FTC, so you might have to check that with someone else

FTC allows you to use the Protoboard, nothing else, not for custom sensors anyway. The SuperPro is really great though, you can even program it separately with a special language.

- Xander

Using Color touch sensor is good. There are plenty of good touch sensors available on Internet. Search on Internet a very less used color sensor for making robot at home. http://www.robogalaxy.com/touch-sensor

IIRC, FTC has changed the rules recently, and you can do a lot of new stuff. As long as your electronics are connected to a prototype board, you can do whatever you want! You have to draw all your power from the prototype board as well, though--I think it provides 22mA? It's more than enough for a basic Atmel chip or PIC.