I love Goduster's motorized dubbing brush maker http://www.flyanglersonline.com/bb/s...ng-brush-maker and really appreciate the workmanship that went into it and some of the great effects that can be created.
Unfortunately, I rarely have a need for anything that substantial, meeting most of my requirements just using the split-thread method, letting the bobbin do double-duty as the dubbing twister. When I do need a full blown dubbing loop, I found a cool little gadget that, with a few small modifications, does a great job - a battery powered baby formula mixer.

I cut off the end of the plastic wand and inserted a de-barbed, dulled-down Tiemco 200 hook (broke the eye off) into a pre-drilled hole with a little epoxy

quick demo (just used some rabbit dubbing here; you can use other materials to make some interesting effects)

create loop and insert dubbing

insert hook in the end of the loop

a couple quick blips (not sure of the rpms but it spins pretty quickly) and it's tight

take your favorite dubbing teaser (a velcro'd popsicle stick works great) and rough it up a bit

wrap the body, tie off and rough it up a little more as needed

The mixer set me back about $6 and 15 minutes to put it together; you can find them at any of those baby superstores.