Another plus to building open projects (L shape or U shape, or N shape or C shape (presumably depending which way you hold the thing)) is that once you have a nice fit on the sides of the joint, you can see if there are gaps on the inside / outside of the pin board, and then re-score the knifewall and re-pare which lets you fine tune the joint and only makes the pins longer. (Doesn’t work on the tail board though.)