A reversed enlarger lens makes an inexpensive macro lens, except that they usually only stop down to f/22. I put a nikkor EL lens in an inexpensive press shutter for that purpose. That is the rig I used until I discovered that the Nikkor 120 AMED lenses are a dime a dozen and they work well with closeup diopters. The only issue is that some enlarging lenses allow some light in on one side to illuminate the aperture scale, but you can put black tape over that.
With a bellows system, you can get almost any enlargement you want... though of course the exposures can become quite long. That can be good- when your exposures are long then you don't need any shutter at all.