It's a low-key, genuinely interesting 45-minute experience where you watch a working replica of an 18th-century hand press in action. A printer demonstrates setting type, inking, and pulling sheets the way Isaiah Thomas did it. You'll see the physical process that produced early American books and newspapers, and you usually get to pull a print yourself. The room smells of ink and paper; it's hands-on without being touristy. Expect a small group of 8-15 people and a knowledgeable guide who answers questions well. It's more demonstration than interactive workshop.
Best time is spring or fall on a weekday morning. Summers can feel crowded with families, and the building isn't air-conditioned. Plan on $15-25 per adult depending on whether you add the optional tour of the library's reading room and collections. Kids under 12 usually get in cheaper or free. The full experience including the print shop and a brief look at the rare book collections runs about 90 minutes.
Pick the printing demonstration if you're into history, books, or making things; it's one of the better living-history experiences in Boston because it's authentic rather than theatrical. Skip the add-on library tour if you're short on time or not deeply into rare books—the print shop is the main event. Wear comfortable shoes; there are stairs and the building is old.