GP hinge slot machine is the best tool I can think of, before I got it I used to spend two days on hing slots not to mention the mistakes and the finger cuts now it takes me about 20 minutes to do slots for the whole airplane, without it hinging is my least favorite part.
I'v been using it in the past 2 years on something like six airplanes, didnt need replace blades so far but I got a cutting guide http://www3.towerhobbies.com/cgi-bin...?&I=LXPU13&P=7