I don't want a rectangular base for my round light, so I've decided to design a round PCB this time.  Thankfully, OSHPark doesn't care about the shape.  I was a little concerned about the rounded-rectangle shaped plated holes for the barrel jack, but it turned out perfectly.  I made a couple mistakes on the silkscreen by keeping a label that was supposed to be hidden and swapping the "-" and "I" labels for the regulator.  Otherwise I'm pretty happy with how it turned out.