can I get some ideas here? For reference: http://en.wikipedia.org/wiki/Isolation_tank, http://en.wikipedia.org/wiki/Sensory_deprivation

Using a bathtub will not work.

Pardon me for asking, but why will a bathtub not work? It seems like a good base, given it's big enough.

Its NOT big enough, which is the problem. In order to experience true sensory deprivation, you have to be able to float freely without your body touching anything. I suppose somewhere out there they sell super-large bathtubs for tall fat guys, but it would probably be easier to build an isolation tank from scratch.

Careful with that thing you might come out a monkey like in altered states!!:D
If you look in the paper people sometimes give away old hot tubs.They just want them removed. A friend of mine got one that way.

A dome tent inside a kiddie pool? You could probably paint it to block the light or put fabric over it. Or if you want to spend more money, you you make one from fiberglass resin or heat formed plastic. Or make a box out of wood and then coat it with cement.

im pretty sure you can buy those inflatable mini swimming pools

those inflatable pools with a cover