If you are using lots of strips, cutting your own makes sense, I use 2 white and one red each season, so cutting them makes sense, otherwise buy them, some are better than others..., in two sizes...
I do the same a Ray's suggestion, a rack is neccessary for good cuts. First, square of the skin, use the trimming as dubbing. I made cutters of different sizes (width) by using Shick Injector razor blades. You can do the same by splitting two edged razor blades. Just cut spacers exactly the size of the strips you need and then glue the assembly together with one top and one bottom piece. Blade-spacer-blade-spacer etc. Make sure there is enough wood contact on each spacer for the wood glue to take hold. Duct tape holds the lot together. The blade is about 1 inch long and the cuting edge is about 1/2 inch with the other 1/2 inch glued in. For cross cuts, I'll wet the hair enough to comb it straight, when dry, then I cut! My cutters typically last for 6 skins before the blades get too dull for good cuts.
Pete AKA Frenchcreek from Calgary