I shop in thrift stores a lot to find materials for my projects. On my project list was a drill press to finish home made PCB's. I found a vintage hobby microscope that is perfect for the job.
Then I bought a rotary tool at Harbor Freight for 7 dollars. The tool fits very snugly inside a short piece of 1 1/4 PVC sch40 that is modified to replace the original eyepiece.
The base is 4in square. The throat depth is almost 3 inches. There is no return spring, but the rack and pinion gives plenty of control for drilling.
No mods to the tool are necessary. But...I couldn't help myself.
The wallwart supplied has a 12v output with barely enough current to turn the motor. I Googled the motor Part# and found it rated for 24v. I now run it from an 18v 5A power supply and the performance is more than adequate for the job. I also added a PWM motor speed controller (that little circuit board on the table).
You might get really lucky and find an old microscope at Goodwill, but first I would raid my kid's toy box. Raid your neighbor's toy box, too.