I have a number of rotary tools that I use all the time. I wanted a quick method of securing them so my hands were free to hold the work, and a method of setting the height for cutting operations.
However, being broke it had to be very cheap, very simple and very quick to make using only the rotary tool and some other readily available tools, like a ruler and a cordless drill.
Step 1: Materials
A base (I'd recommend using 3/4 or 15mm MDF, plywood or similar).
4 off 100mm (4 inch) M6 (1/4 inch) bolts
4 off 'Nylock' nuts to suit the above
8 off standard nuts for same
16 washers for same
An emergency pipe repair kit.
Depending on the pipe repair kit, you should be able to mount a rotary tool up to 2 inches diameter across the body, as long as it does not have too many compound curves. I doubt it will work with the very 'ergonomic' designs.
I was using it for a MiniCraft Drill and the Extension shaft drive of an El Cheapo tool.
The pipe repair kit consists of two pressed steel plates, two strips of dense rubber and 4 nuts and bolts.
Step 2: Preparing the Pipe Kit
I discarded the nuts and bolts which went into the 6M jar for some other project.
I offered the plates up to the MiniCraft Drill, but they were a bit too long for the small body of the drill.
I cut the end off using the Mini Drill and some grinding disks (it used up one disk for each end, tough steel!).
I then trimmed the rubber to fit.