Guys, the tape (gaffer or darkroom, not duct, please) and cardboard solutions you proposed, also the foamcore solution you didn't, are pretty half-assed. More exactly, they're not secure and don't guarantee that the lens' axis will be perpendicular to the film plane.
Anupam has a tiny little lens and not much solid he can butt it up against before taping. That's why taping is a bad idea.
Anupam, I don't approve of it but there's another solution that hasn't been suggested yet. Drill or cut a hole in a Nikon body cap that's a little smaller than the front of the lens. Then epoxy the lens to the body cap. Or make the hole exactly the right size and insert the front of the lens into it before gluing.