Starting with the stainless steel bowl for the tuna, I found that it fits perfectly inside the plastic container that CDs come in. For the feeding bowl you use, you may need to find a different container it will fit into. That container, in turn, needs to fit inside another plastic container. Leave an adequate distance between them for the water moat. The moat has to be wide enough that an ant can not reach across it without swimming, which they tend not to do.