Routing out the 1/4″ deep mortise on the bottom and edges of the walls. After getting the right 1/4″ depth, I setup a straight edge which provided a border that prevented the router from traveling outside of the area I wanted to remove. I then slowly worked my way in from the outside edge to the guide.
The first mortise is complete. The fence worked wonderfully.
You can see the 1/4″ mortise in the 3/4″ wall. This ledge will rest on the edge of the deck.
Getting the curves were a bit of a problem as I used the inside of the inner template as a fence. It didn’t quite match up so I had to do it in 1 foot sections. I couldn’t use a flush trim bit in this case since I couldn’t cut all the way through the material.
Both walls are complete!