Gouges aren't made out of pipe, they are either ground or forged, and the simplest thing is to buy some flat stock like O1 tool steel that is available just about anywhere, heat it red hot and use a ball peen hammer to tap it into a swedge block. Not having had any luck finding one of those, I would either just cut open the right piece of mild steel pipe or tubbing, and hammer it in there; Work it over the horn of an anvil, or even make a hollow in a block of wood, yes it will instantly fire up, but it won't loose it's strength so you will possibly get the gouge shaped before you have to put out the fire. Haven't tried it, but it might work.
There are two great books on making your own tools. Alexander Weygers, a tatented sculptor, made all his tools out of basically scrap. He wrote 3 books that are now published as one volume. In my area, most libraries have access to this one.
There is also a good book on more modern production techniques for a one man shop, Called Tool Making for Woodworking, by Larsen.