With Booth3 you can have users type a short message on the print or other output. Options include the location, font, text color and how large an area. Here are the details for setup.
Start by going to the Text tab and checking Photo Note, You can also customize the prompt there too. (see item 1 below)
Next, go to the print template and create a text box and add %PhotoNote% in that box. You can also use the Insert special text menu under Other (see item 2 below)
Adjust the font, color and location of the text box and you can also set Word Wrap and right, center or left justified for the text.
In the session the user will be prompted if that want to add a note. The text they type will be added to the output, if they skip that the area will be left blank.