I know they say to use a camera lens... something optical gurus frown upon since camera lenses are mostly curved field optics. An enlarger lens is a flat field. But many macro lenses also happen to be flat field... go figure.
I know if you have a Micro Nikkor and a spare lens cap, it can be turned into an enlarging lens by drilling out the bottom of the lens cap. You also gain a nice focusing mechanism at the same time.
