I really want a unity volcano -
 Like a science fair volcano where FI and I pour vinegar together and  there's a big pretty erruption and it envelops the tiny village we've  constructed at the bottom (maybe even a tiny Jurassic Park - the world is our oyster at this point).
 FI and I really love building things and doing projects together, and  when I brought this idea up to him, he got really excited and started  drawing up blueprints. I think it's going to be fun. He's an ecologist,  so science gets him excited. I'm an English teacher, so Jurassic Park  gets me excited. This feels like a perfect marriage in unity ceremony  form.
 My question is this - how can I discreetly present the volcano, do the  ceremony, and have it carted off again? We don't have a venue yet, but  we're looking at a backyard or a park. Something open and grassy.
 Any ideas?
 Also, how do I keep my FI from wanting to make it 6 feet tall? He's  already trying to figure out how to make tiny electric fences.