Here's my second contest entry. It is similar to my previous topic , but previously I showed how to deal with thin material being joined. The method I show below improves the classic method of mid panel joinery in 3 ways. First, it creates a positive stop on all pieces, instead of trying to align pieces to a drawn line. Second, there is only one measurement made, so you can't screw up to get a misalignment. You still could still screw up and get the shelf in the wrong place... My set of parallel guides (based in large part on the various ts55 parallel guides out there) is the key to these advantages. Third, the one measurement needed does not need to include the width of the shelf material. In the classic method, when the boards are in place ready to be dominoed, the easy measurement that can be made is from the bottom of the side to the top of the shelf. This is occasionally what is needed, but more often I have found myself needing to place the bottom of the shelf relative to the bottom of the side (or top to top). Utilizing the scrap of shelf material is the key to this advantage.