I had quite effective results in one instance applying a capo to a pair of spoons. A "wire tie" slipped around both spoons at the base of the "bowls" so as to hold them tightly against each other significantly improved the tone.

Unfortunately, the owner of that particular pair of spoons lacked the artistic virtuosity to extract any sound at all from them with the capo thus applied, so I was forced to remove the capo for him after the audience had enjoyed a brief respite (since he actually was a good friend, only occasionally mildly annoying, and mostly quite pleasant to have around).

John