Joybell - I bought myself one for Christmas this year for much the same reasons, and mine is also green.

I love watching the way it starts off from cold too, forming structures a bit like the "black smokers" you see in deep water natural history programmes.

My OH just goes on about surface tension and immiscibility (sp?) and things like that but I find its shapes soothing.

I think the ones in the link above have been speeded up. Mine takes an hour to get going, and then gradually speeds up, with the wax risers getting smaller as the temp goes up.

It came with instructions not to run it for more than 6 hours at a time.

Paws