Backstory: My friend's sister got married a few years ago and she had to manually print and cut all of the place cards.
The idea: Wedding place card software.
Deep Dive: At her wedding, with 180 guests, you can imagine this took a long time. It would be great if there was a software where you could import your guest list, assign them tables, and then print out place cards using whatever design you like.
Validation: Shortly after my sisters wedding, I found https://www.placecard.me. This is a really good solution, but that doesn't mean it should be the only solution.
Monetization: You would charge a set amount per card printed, you could have discounts for larger orders.