Stoppers have been put in one manhole and the other manhole filled with water.
In particular cork is the natural material for make stoppers for wine.
Later examples have screw in pottery or metal stoppers, or a simple push in cork stopper.
Things like personalized shot glasses and Page wine stoppers may be gender neutral, but keep in mind the ages and people attending.
Leaf shaped favors such as candles, coasters, book marks, wine stoppers and vases.