Gordon Meyer wrote:Unfortunately, changing even a single character of the contents causes radical differences in the barcode. It will take some clever manipulation to create a barcode that remains valid after you've erased or added spot or two. Who's up to the challenge?
Still, even with a radical difference, I guess that the difference is difficult to see - one bar code looks like any bar code. So, perhaps a more practical and less messy solution can be found.
For example, begin by showing a card with a bar code on.
-"Let's put it a side for safe-keeping for now. We'll return to it later."
and put it in a Himber Wallet, where another bar code card is hidden.
A 2-way out effect can now be done. A switch might be considered unlikely, since you actually showed the bar code in the beginning.
A multiple out effect could probably be constructed along the same lines.
The "Out to Lunch" method also comes to mind.