2 night ago, I was able to re-cut some of the letters in an effort to not have any broken pieces. The S and W continued to split on me, but I was able to get a nice M, A, and B so I will count it as a success.
Last night was fairly productive. I was able to use my router with a 1/4” bit to cut a dado in the 4 sides of the frame to accept the plywood bottom. The 2 shorter sides had to be stopped dadoes so that they would be hidden when the frame is assembled.
Once I cut the dadoes, I set to rounding over the “fingers” for the joints. I wanted the roundover to go as far down as the next piece would cover, so I marked all the joints 1/4” from the end, and pulled out a rasp.
To roundover the edges, I cut a 45 angle on each side with the rasp, eased the resulting edges, and then smoothed over the whole face.
This is the result:
I continued that process for all of the fingers at each of the 4 corners. In the end, it will give me joints such as this (This joint is a bit off since it’s not the actual 2 pieces that will join together, just happened to be the order I grabbed them)
After I got all of that finished, I put everything together for a dry fit
-- End grain is like a belly button. Yes, I know you have one. No, I don't want to see it.