I was thinking of grabbing my holesaw and drilling some holes through the top for the yarn to pass through, apparently on the floor gives the unwinding yarn further to travel, letting it unwind freely, sending it through a hole restricts this again making the result similar to sitting it on top, which I think works fine, no crawling under the table to change yarns etc. I also thought a big hole might work, instead “big hole” = “black hole”

As for the wheels, I’m planning to put wheels (locking is a great idea) onto one end only (sort of like a wheelbarrow), possibly seating each side pair of legs into a piece of timber for added stability – they don’t look very robust to me, also, adding wheels one end makes a height difference. I like to be able to “undo” projects what don’t quite work, so cutting the legs that the wheels are going onto, to make the table level, is against my grain. I will see if adding the timber makes the whole lot too high, cutting the legs down to take the wheels might be my only option.

I think there may be a page dedicated to adding wheels!