Here it is after a trip to the angle grinder. The cuts are a bit straighter and, on the back, which you can't see in this picture, the edges are beveled, which should make them fit together better. (This is likely to be pointless and theoretical, since they probably won't fit together very well anyway, but I figure it's worth going through all the right motions, just to get a good education.) I started removing the rust to make the welding a bit easier (true, but not necessary and perhaps not significant), but then I kept going just because I liked it all shiny. Even though I was about to turn it black.