Does anyone know what kind of indicator I shouls be looking for to build a spine tester? What brand or type?
Just pick one up off of Ebay. If you look you can find a new 0-1" dial indicator for around $14 bucks shipped. I am building one and that is what I paid. You are looking for one with a big round dial with a stem sticking out of the side of it that moves in and out.
You could also use a protractor for about a dollar at the dollar store.
If you go with a dial indicator, make sure it has at least 1" of travel and check the spring tension, if it's too stiff you may have to counter it with the weight somehow.