The batch I was after is what I use for a 'Golden Stonefly' nymph.
You first need a coffee grinder. Walmart's got a cheap one that works fine. I would not recommend using it for coffee after you start making dubbing :)
(Never turn it on with the cover off and stay away from the blades with it plugged up.)
You can buy raw materials for your dubbing at craft stores and such for a few $$$. Remembering grade school art class you can make a lot colors from the 'color' wheel. ROY G BIV (Red, Orange, Yellow, Green, Blue, Indigo, and Violet)
Measure off a few strands of the colors you want to use. I go approx. one foot of each color.
Chop the strands into pieces about 1/4 of an inch.
Put them into your coffee mill. Be sure to pulse the mill. I found that running it 'wide open' caused it to not blend as well and it wrapped the fibers around the blade.
Make note of the ratios of each color when you get a batch you're particularly happy with. I use small craft store zip bags and write ratios and colors on them with a permanent marker.
Note: You can also use the mill to blend natural dubbing with synthetics and sparkles just as easily.
I will not say that this technique has stopped me from ever buying dubbing. There are types that this just isn't as good as but it will give you another avenue to become a little more self sufficient. It's sort of cool being able to make dubbing when you need it.