Here's a work-in-progress photo from last night, after the main panels had been painted (I did the sides after taking this photo). It took about four coats of the chalkboard paint (I used the Rustoleum one) to get a nice thick coating, and it'll take three days to fully cure. I'm going smooth it out with a fine-grain sandpaper on Friday, check if I need to reapply another coat anywhere, and season the chalkboard paint (You rub chalk all over it to block up some of the pores in the paint) if it's totally cured.
Really looking forward to trying this out at the table. Depending on how it works, I might try a second version using the rest of the paint and magnets that's made of unmounted wooden panels with glass cabinet hinges (no-screw clamping hinges) holding it together. Wish me luck!