Kind of like the fact you managed to create that so it lines up with the holes currently in place. I have the same concept in play, with a Mole support board (it works great, and very versatile - just need to cut the base, but still deciding how much to leave in place). Going to mount it in front of the two fold down door shelves located on each of my barn doors. Mine needs to allow for the panel to be easily removed for access to the storage behind those shelves.
Would have liked to design it myself as you have done, but never considered 3D printing - creative approach for sure.