Very nice. I have a similar project languishing on my poor, ignored workbench. You may have inspired me to change that. Good typing to you!

I think folks would rather know. If it’s a split group, you could tailor the invites to mention that it’s also the other kid’s birthday, but they have their own group of friends coming with gifts.

That’s the hay loft. Probably more so on older barns, but that’s where the term is from.

Nitrile gloves have been shown to offer a bit more protection against isocyanates than latex. If you’re just worried about mess and aren’t allergic, then probably doesn’t matter.