I am trying to make a fissure vent volcano instead of the normal mountain. Thought it would be a neat idea to have a container of CaO in a thin plastic container, add water and produce some steam. The heat would hopefully melt the plastic a little and drip into a container to produce the (hopefully more exciting) vinegar/baking soda reaction for magma. I think that the CaOH2 that would form would not produce the gas I would need to foam a soapy vinegar solution, though. Any ideas? Would adding washing or baking soda to the water that combines with CaO make it happen? Better ideas? I've been out of chemistry for a while. So I'm making sure there are no dangerous/pointless steps happening. Thanks!

It won’t produce any gas AFIK, just calcium hydroxide and then calcium acetate. What’s wrong with just using baking soda and vinegar? You could add dry ice if you wanted a nice smokey  effect.