I guess I work my little dremel hard but it just died the other day 

For my dremel, I cut up a dust mask and secured the pieces over the vents on the tool. I replace the pieces of mask when they start getting a bit clogged up. Works very well, no issue with the tool overheating and no issues with dust. Prior to doing this, I went through 3 cheap rotary tools, and took the occasional electric shock to the hand during operation...