The 1960 edition of Scientific America's Amateur Scientist book has a chapter on microscopes. In it, there's an explanation of the single lens microscope and how to make the needed tiny lens. This may be the way Antonee van Leewenhouck, (1632 to 1723) made some of his lens. I replicated the microscope back in December 1985, but it wasn't close enough. Still, I was able to write a small book on it in calligraphy for the SCA.
With the help of a machining teacher, Frank McSherry, I was able to improve the design to come up with this one below.
Through these single lens microscopes, I've been able to see details in insect wings and legs and protozoan.