Nyle Steiner gets a link from me again, this time for his construction of T.E.A. lasers. I remember reading about these kind of lasers in an issue of Scientific American (I just looked it up, Jun, 1974 in the Amateur Scientist column), but that was the extent of it. Nyle has done a lot of experimentation and written up his notes here.
These lasers in most respects don’t compare favorably to the ubiquitous laser diodes that we’ve become all-too familiar with, but they don’t require any ability to fabricate semiconductors, blow glass, or indeed, have any machining skills beyond the kind you might have if you can find your way around a Home Depot.
He’s got some YouTube videos about these, oddly enough, that don’t seem to be linked to the above page. Search for his name on YouTube if you want to get more of these: