I've been fooling around with Dremel tools for about thirty years, and I regard them as about the most useful power tools for model building. But I also have a major beef with Dremel.
The first one I ever got (I won it in a contest, at a time when I wouldn't have been able to afford to buy it) was a single-speed, non-ball-bearing, corded model. (They didn't make the cordless ones in those days.) I quickly found out that it was almost useless for plastic modeling, so I sprang for about $15.00 (this was back in the early seventies) and bought a Dremel "Tabletop Speed Controller." That solved the problem beautifully. If I turned the knob on the controller all the way to the left and turned on the tool, it would stand still; I could then put the drill bit exactly where I wanted it and, with the other hand, turn the knob to the right until the motor was running at just the speed I wanted. Great.
Since then Dremel has introduced all sorts of Moto-Tools, with each new one boasting that it's faster than the previous one. To my notion, the company is ignoring one of its markets: to model builders such high speeds are irrelevant. Most of the current versions have 5,000 rpm as their minimum speed. For jobs involved in plastic and wood modeling (at least in ship modeling, which is what I'm most interested in), 5,000 rpm would be a good MAXIMUM speed. In my experience a #70 or #75 drill bit will drill a clean hole in a piece of styrene or hardwood at 5,000 rpm IF the bit is sharp. If it's even a little dull, though, the plastic will start to melt or the wood will start to smoke - no matter how gentle the pressure applied to the bit.
My dear old single-speed Moto-Tool long since gave up the ghost, but I still have the speed controller. (It comes in handy for all sorts of things - including varying the heat of a soldering iron and changing the size of the picture on a portable TV. Never mind how I discovered that one.) When I plug my more recent, adjustable-speed moto-tool into it I get mixed results. I can slow it down somewhat below 5,000, but it stalls at a slightly lower rate than that. I also have a battery-powered "Mini-Mite," which actually does pretty well for most purposes - but even its minimum speed is faster than I'd like for drilling with small bits.
Some months back I found, in the Woodcraft woodworkers' supply catalog, a small motorized tool made by a German company called We-Cheer. After some thought I bought one, and I really like it. It's slightly larger in diameter than a good-sized fountain pen, has a chuck that's interchangeable with the standard Dremel ones, and has no speed control. When plugged into my old speed controller it can be adjusted down to zero - just like the good olde days. (I suspect a simple plug-in rheostat, or even a dimmer switch, would have the same effect.) I haven't had it long enough to comment on how well it will hold up over time, but so far it looks like the best such tool for model building I've found yet. And it only cost about $25.00.
Dremel - if you're reading this, give us a small Moto-Tool with a built-in speed control that runs from 0 to 5,000 rpm. Model builders will thank you.