I prefer using old tupperware for my pans. They cut easily and can be carved with an exacto knife. The center tube needs to expel the air you are pushing against when dipping. The bigger the diameter the better. I keep the tube below the container a little so that it does not flow over the top. To ensure an even rim, level your dipping pan using a level and shims if needed. Rest the pan on blocks of wood or on top of a coffee can, so that the downspout is clear of your table top.