One of my favorite macro rigs comes from a "Compugraphic" typesetting machine, which had a turret on which various small macro lenses were mounted. Most of them fit into a microscope adapter, and a few that did not were easily machined so that they do, and the result is a few that work very well, with varying magnification. Apertures are a little dim, but they're pretty sharp.
I'm too lazy to go back and find the NEF originals now, but here are a couple of small JPG's made with the D3200 and a couple of those lenses, which ones now forgotten: