It's tough to be square

I'm gaining a new respect for carpenters and people who build things for a living. Do you know how difficult it is to make something square? It seems pretty easy, right? Just put two pieces of wood together at a right angle, add some screws and maybe some glue, and ta-da! You have a corner. BUT is it a square corner? When you add the other 4 sides of the cube, will it actually be a cube, or some sort of lopsided shape that is NOT a cube?

I have a tri square (my dad's) and a... not-tri square (my neighbor's), and a 'light-duty corner clamp' (from the hardware store, it's really cool but it broke the first time I tried to use it so I will be taking it back). The squares are great for learning if your corner IS square or not, but if (or rather, when) it's not, they don't magically fix it for you.

ANYWAY it's fine, my little Walden is coming along nicely, and it's VERY CLOSE to square. Yes, there is a small (eighth-inch?) gap in one spot, but it's under the overhang of the roof and also I bought some amazing silicone outdoor caulking that I applied today, which I think is going to solve all my problems. And I'm going to use my sander to sort of tidy up the edges that don't quite line up perfectly, so it will sit squarely on a table, and then we should be all good. I hope.

So today I attached the back wall, did some caulking, and also did some more staining of the various bits of wood to seal it against the weather and make it pretty. Next I get to put the ceiling and the floor in! The ceiling is going to be the hardest part, but the floor should be easy. It's coming along! Right now it has a roof and three sides. Yay!