i think u mean 'RELAY'.. 85 (is switch '+' teminal),86( is switch '-' or ground), 87(is your consumer's '+' teminal.... cosumer like horn or blub)...and 30(is the direct battery supply.. u might wanna put a fuse for this line).... hope info like this can help... if u need to learn more go to howstuffworks.com and find out... :)
I made one myself at home ,
i think it works not bad ,
material = plastic bottle , gas hose < i'am using 9mm transparent type > and sponge like thing that you often get when buying delicate items like computer...