I put a little tuna in the can, left it over night and bingo.
Step 2: Cutting Windows
In two of the pieces from the previous step cut holes for windows. In my case I cut a hole in each piece approx 6"x16" because I had enough scrap plexiglass to cover it. I imagine you could use chicken wire or anything else, but I think the trick here is to create windows that let in enough light to be able to view whatever critter you end up catching, which is why I don't think just a few small holes would work and large holes would probably get chewed on.