I just keep a stencil in my tackle box. Put a few black dots and whamo, instant speck!
Cooked a bunch for some friends. One buddy in particular claimed he didn't eat them and he could tell the difference. I told him that I would give him a taste test. I put sandies in both plates. He tried both and said very convincingly, "Oh, that's a speck!" I said, "Man you are good!" Didn't tell him for along time.