Specifically, it's 24x28 with 10 ft ceilings. That's 3x7 = 21 4x8 panels. Plus walls, per your suggestion, 6+6+7=19. So 40, but would need a few more for the top 2' sections and the front wall. So maybe 40 was a bit of a low-ball estimate :/.
I would like the rest of the shop space to be...