how large should the nest for robin be, if speaking in dimensions of an open box? my hubby finally made one... not beautiful at all and pretty clumsy... I wonder if it's going to work.

The internet says a robin's nest is about six inches across, so that would be the minimum size needed for a nest to fit inside it. Somewhat bigger than that would be desirable since you're trying to provide a landing platform for babies that fall out of the nest. I get the impression that the adults like to be able to see their surroundings while they're sitting on the nest, so the side walls should be fairly low.

thank you, but no - I am not building a landing platform, I hope the bird would pick my wooden box for the original nest. A whole idea is to place this not on the tree but under the roof of my house providing protection from the heavy rain and high wind. I saw once that one bird had a nest that she connected to a rain water pipe that was also under the roof, and it was a success - no accidents.

this is what it looks like (ugly, I know). I was tempted to put some bedding inside but I didn't. I know that the front wall could be shorter but it's really difficult to argue with my husband who finally assembled it when I wasn't home. The wood started to split at some places (but it's still sturdy enough) so he said he won't change anything. Made of wood scraps.
Pardon out Xmas decorations

I'm not sure they'll like it since the side walls are so high. But it's a nice protected area so some kind of bird might like it. A cockatiel would love a box like that lol.

The x-mas lights up in the middle of April makes me like you a lot, Chipper. Like if I weren't married and straight, I'd ask you to prom or something. Hehehe!

If it was a little larger a chicken might like it too.

I'd sort of like to have chickens, but the homeowners association would never allow it.

you see, my neighborhood doesn't care about Xmas lights or even chickens. Several people around here have chickens, as I know. Now we have lots of wild ducks wandering around. I see them sitting in people's front yards. I guess they are about to breed. The neighborhood is rather decent (or should I say - not too bad?) from one hand, and rather liberal from another.
I am glad you like me, Cloudy Skies. I would go to a prom with you Keeping lights up makes it easier to be festive when December comes:) Ours are there for... I am guessing 2.5 years now.

If I put some bedding in, it would elevate the floor level and would make side walls shorter. You break my heart, ladies, saying that it's only good for chickens

so how tall should side walls be? I thought chicks would fall out if walls are rather short.