Perhaps something like a 70-300 zoom would work well enough. The Nikon one might not be able to focus close enough, but some of the third party ones could be better. They aren't 1:1 'true macro' but might be worth trying. I've got both the 70-300 and the 105 macro, I'll see if I can get some shots later tonight and see how they work (I've been meaning to get my photo setup going anyways
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Another option (I've never tried) is a close up lens on the front of your existing lens.