A person could do more than 1 a minute. The SAT writing section is 44 questions in 35 minutes. That’s less than a minute to read and process the answer and mark the choice. A math section is 25 questions in 20 minutes.
10 Seconds max if you’re just filling in 1 spot, then taking a new one out of the pile. 50-60 people could do it in the time given.
If I am off by a factor of 6 then that would imply 418 / 6 = 70 ballot drones would suffice. let’s say everyone is organized into minivan sized squads with a clipboard ballot sergeant in charge, and the clipboard person does double duty as a drone. i’d say 6 people per minivan. 70 / 6 = 12 minivans, each with a clipboard ballot sergeant in charge. all the clipboard sergeants are being directed by a couple of ballot factory captains. they coordinate over cell phones. that is roughly 70 + 2 = 72 people. there might be more organizers directing them. something might eventually trace back in the direction of a “general stacey.”
i dunno, but it sounds feasible, especially if they had some advance prep drill, or the factory was already in place for a plan b operation. if they already had a stash of pre-filled ballots, it could in theory reduce the number of people involved by another factor of D where D is the number of days advance prep. For example, if D = 7, that would yield 72 / 7 = 10 people. For an illicit ballot factory, you want to limit the number of people involved to the minimum possible to get the job done.