As you get to pounding them out, be sure to save every little scrap of sheath or short fiber that gets combed out. Get yourself a baggie and just keep sweeping up these bits and bobs, adding to the bag as you go. When you get about a quart/liter baggie packed full then you are ready to start cooking.
Wash them in barely warm water with a drop or two of Dawn dishwashing liquid, rinse, repeat. This helps get rid of residual fats and greases. Simmer these scraps in distilled water below boiling for a couple hours, adding more distilled water if it gets low. Strain out whatever solids remain. The liquid should be a very firm gelatin at room temp. You can cook it down more to firm it up, or add warm water to thin it down. I like to cook mine down so that it gels into a pretty tough gelatin at room temp, then I run it though a cheese grater, spread out on cookie sheets, then set it where there is good air movement to dry the hide glue down into pellets. I store mine in the freezer no matter how dry it gets because 1) any moisture at all and it MOLDS, 2) I got clever dogs in the house and this stuff is irresistible.