spring loaded scissors, and i do mine as i go so i don't have so much to do at the end (as i sew a section together i go ahead a clip any seam that isn't going to be needed again, so by the end of constuction all i have left to clip is around the outside. i don't know if it is faster that way but it sure seems like it, and my hands are not cramping up on me later....also, if anyone is around (kids, hubby....) i hand out scissors and draft help :)
it is a tedious job, but well worth the results.