Hi Colin,
Try this thread:-
Thread in fixed and gone.
In my opinion a disco type smoke machine makes far to much smoke. you only need a very small flow of smoke. Will try to find a moment to take a picture of how much mine makes and post it tomorrow. I set mine to make too much first and had to turn it down, I have an even lower setting for long run times.
I had a day or so with no work and turned it into something very useful with practically zero outlay ( I think I had to buy the baby oil). Certainly it will be useful and if you've got a little more time than money then homemade can be a way forward.
If you decide to go homemade then feel free to call me or post for more info.
Shaun.