re: Quintuplets

I make the base as a separate assembly from the box initially. That way I can cut the keys (splines) in the box portion as seen in the photo above. Once the splines are done, I then attach (glue) the base to the underside of the box.
The base is a mitered frame with a groove to accept a plywood panel. The plywood panel I used here was cherry veneered plywood. I cut a decorative arch in each of the four pieces of the mitered frame. Doing so gives the appearance of feet in each corner. I posted a photo below from another box I had just made. I did the base with this box the same way as the boxes in this post. What’s different is the panel is a piece of MDF I painted black.

Hope my description helps. Below I posted the project link for the box in the photo. The steps are essentially the same. And if you look at all the photos in the description then you will see the box and the base photographed together before I assembled the two together. Let me know if you have more questions. Be glad to help.
Link
https://woodworkingweb.com/creations/1467-chatoyance