🚀 go-pugleaf

I haven't built an STM, but R.A. Lewis, S.A. Gower, P. Groombridge,
D.T.W. Cox, and L.G. Adorni Braccesi published an article
"Student scanning tunneling microscope"
in American Journal of Physics (ISSN 0002-9505) Volume 59, Number 1,
Jan. 1991 P38-42

The abstract was, roughly:

 A scanning tunneling microscope (STM) has been constructed as an
 undergraduate project.  Its mechanical and electronic design are
 described and results obtained using it are presented.  At the same
 time, the requirements to be met in STM design are noted.  Design
 developments which have paved the STM's way into the teaching
 laboratory are identified.

I don't have the article in front of me, so this is from fuzzy memory:
The authors didn't quite get atomic resolution, but it was close.  It
looked like a $1000-$2000 project, but I haven't looked for prices on
all of the components.  I think that they used a chart recorder or xy
plotter rather than a computer to record data.

                                               -Jeffrey Soreff

standard disclaimer: I do not speak for my employer.