It took longer than I wanted, but my son's room is done! Many thanks to the folks here who shared their thoughts on wall repair and LED strips. This project took longer than I wanted, but every step was done right.
Most people who make geometric mountain walls seem to use boards at 45°, but that would have looked awful with the 36° ceiling slope. Matching the cut angles was much harder this way - lots of math and some jigs on my miter saw - but I like this look more. It feels more like the White Mountains where we vacation as a family
The Pinterest examples my wife sent me for inspiration all out up the boards with construction adhesive. These are put up with 2.5" finishing nails into studs, filled, sanded, and caulked before painting. This feature is permanent, but it can be removed like any trim without tearing down the drywall as well.
I had the notion to hide an LED strip in the upper mountains to create a sunrise effect. The actual lights are much more subtle than it looks in the pictures. I wish I knew how to get better photos of LED setups. Of course he can make the LED strips do rainbow zoomies and other such delightful nonsense because he is 11.
Our goal was to make something that will appeal to him now and as he gets older. I think we hit the nail on the head with that, but we will see in time.
Thank you again to everyone who shared their thoughts as I built this.
Holy macaroni, that's gonna make for one happy and lucky son! Kudos!