Thank you for the responses.
Do you have a link for purchasing it online Paul? When I wrote the post I was thinking about the non-repeatable nature of the effect but it seems you have solved that.
As far as the original concept of the trick...
I have a grasp of trademark, patent, and copyright law but the whole matter gets a bit hazy when it comes to some (especially older) tricks/effects. There is also a wider gap between ethics and legality in magic. However, I do like that most work hard to credit predecessors as necessary. You don't see that in any other trade.
There are several old tricks I'd like to revamp but that is another discussion for another time. It would be great if there was a written resource directly relating to these issues in magic. If I do begin creating commercial products the last thing I want to do is harm any friends in the community through my own ignorance.