It's better to explain things on a personal level, perhaps show them some hand carved stamps. If you have an idea for a stamp for their store, show them the image. You could print out info to leave with them for them to read at their leasure, but talking to them would be more effective, spending some time with them.

If the place is really busy, see if there is someplace you can put the box where no one working will have to stop and get the box. And sometimes personnel changes and the new people don't know about the box. Or if they are really busy, it could be a pain for them to stop and give it to you.

MM