Thank God for wood putty. My mom's task was to build her a bookshelf for the new library. Problem was, it had to be made out of pine that was 3/4" thick. Of course, the wood wasn't perfectly straight and it was difficult to get it to do what I wanted. Plus there were a couple screw-ups. I routed some shelf joints where they shouldn't be, and had to fill them in with putty. And one of the shelves split in two. Yuck.
I built it. Mom is in charge of sanding it and painting it, so we'll see if it will actually hold books when she's done.
Next time I'm insisting on using thicker (non-pine) wood so I'm not constantly flirting with splits and not trying to cram a warped board into a perfectly straight joint.