I have a Krups 203 blade grinder. The Mr Coffee's are also a good model, but some of the models (like the cuisinart) have a weird looking blade that don't look like they would chop the fiber apart and mix them well. I like the old fashioned sharpened straight edge with (with flanged turn down tips) on those bad boys. They can chop. Any blade grinder should be up to the task of blending, just make sure the top cover is a shape that you can work with and that there is a big enough mixing reservoir to hold fibers in. Add a favorite or sticker or two on the grinder housing, as this not only makes the blending job sweeter and faster, but makes you more awesome.
When it comes to making dry fly dub, I don't know a whole lot except that muskrat, beaver, and any of the other water rodents really work well. You're looking for light fibers that will loft up well in a mixer; hydrophobic fibers are even better, as they won't require much for floatant. Singlebarbed has a few great tutorials on DIY dubbing worth checking out. He is the guru of dub.
Nymph dub. I've visited the topic of DIY Ice Dub on here in the past. I like antron, acrylic, and other similar type fibers (trilobal). I like coarse guard hairs like hare, fox, squirrel, woodchuck, etc. Rabbit and hare underfur serve well for bulk filler. ANGELINA. That stuff is the shiznit. It will add flash and sparkle to any good nymph mix. There are different colors and they all produce different effects when used separately or in conjunction with one another. The violette Angelina gives off a purplish sparkle and is what is added to dubbing to give it that "UV" look.
If you're looking for the brands of synthetics yarns I like to use, then here goes:
MCG Textiles rug yarn
Design Works Craft Trim
Craft and Rug yarn from the Hobby Lobby
Needloft craft cord
Needloft is a great antron substitute, but the fibers can become knotted and tangled. You'll just have to pick the nits apart when blending. I try to alleviate the situation by cutting the fibers down to 1" to 1/2" lengths. Pretty much any rug or latch hook yarn you can find is gonna make some sweet dubbing. They are a lot like the "Sparkle yarn" used for caddis patterns, especially by La Fontaine. I typically try to keep my fibers about an inch or so in length, as the tend to blend and mix a lot better. Longer fibers will bind up and even get caught under the blade, making a natty mess. Dread, Natty Dread now...
Keep the batches in the grinder small, too many fibers at once will bind up; not enough and they won't break apart and mix. I tend to chop each type of fiber one at a time. I'll separate the chopped fibers into a few mix piles with the ratios of fibers I want, then blend. When each pile is blended, I'll combine them into one big pile and mix by hand, if necessary. For fur, I'll cut the amount of fur I need right off the skin and into the grinder, chopping and mixing the hair to add loft. One thing with fine furs like rabbit is that they'll become statically charged, which can become a total mess.
If any of you have a brown (or gray) shorthair tabby, brush the kitty as much as possible and save the hair. Collect as much as possible. Put the fur in a ziploc and microwave for a few seconds, put in the freezer, or both. This should kill any lingering microbes that were hanging out with old kitty. Then proceed to send the bag to The roughfisher Command Post, Detroit Lakes, MN 56501, c/o the roughfisher. The cat will love you, and you'll have a plentiful never ending bounty of the world's best dubbing fur. My old tabby made the best dubbing; I wish she was still lurking around so I could get my hands on some of that sweet, sweet fur. I don't know how a medium or long hair cat would work, but a shorthair tabby is like hare fur, but with tons of sweetass guard hairs.
The best advice I can give any of you about dubbing blends is the concept "spectral". Use a composite of colors in your blends to make up one single color. Rarely in nature is an object a single pure color. The object is composed of a myriad of colors that when compiled together blend to form a hue. One example is when I make some orange sow/scud dubbing. The base of the blend is hot orange acrylic yarn and aurora Angelina. I add rabbit/hare (dyed fluorescent orange) for texture and filler. I also add minute amounts of red, yellow, and perhaps another orange colored fiber to the blend. When mixed together, the red and yellow fibers add highlights to the blend, and help complement the overall color base. Same goes for peacock: black fiber base, dark and light green highlights, and peacock and black Angelina. Don't over do it though. A subtle highlight is more effective, as too many extra fibers will dull the base color down.
This Public Service Announcement was brought to you by: the roughfisher.