Reply #55: You wouldn't have to have them in each booth

[CornField]

Now many people mark in a booth and then walk across the room to feed into an OS machine. You could have booths for marking and a centralized booth for putting them into the box.

Also, when it comes to people bringing in additional ballots -- each precinct could be given a special sticker or stamper. When you sign in and get your ballot, the poll worker would place the 'marker' on your ballot. Any ballots without the stamp/sticker would be spoils.

ETA: You actually would not want the boxes in the voting booth -- at least not in a way where they could be seen by the person filling out the ballot. If they could be seen before a ballot was marked, they could influence how that individual votes.