Once you have determined the length and diameter of the pipe, go ahead and measure it out and cut it to length. I use a hacksaw but there is no reason you couldn't use any old saw you got laying around. If you are using a 1.5 inch diameter pipe you do not need to go through the steps on how to taper the pipe. 1.5 inch is fine for slapping on a mouthpiece of some sort and blowing away. Here is a method for forming a wax mouthpiece...
