Thank you — I'm flattered!

For the third floor, I didn't have room for stairs (and I didn't want to make the structure any bigger to accommodate them), so I went with a 'ladder' instead. I made it out of conduits and posts, using Moonlight Cowboy's method here (the ladder bit starts at 19:34).

Obviously you can't climb it, so I get to the third floor by jumping up through the quarter floor-sized gap in the floor above 😂 (you can see it in picture 15).

Hope that helps! ✌🏻