I can't help with the GU10s, but your question inspired me to upload/post the custom wall I made about a year ago. One of these days (when pins aren't being worked on) I'll have to take video/pics with the machines (pins were pulled away from the wall for this clip).

[ The MSF I sold was in the blank spot and obscured the wiring, but the gap will be filled ]

A picture alone likely won't reveal how it's built, so I'll give an idea. I painted the lighted section of the wall with a pearl/metallic white with the expectation that it would better show and reflect the colors (not sure how much difference it really makes). The initial framing was done with 1x2s flat on the wall where all of the LED strips go, and also at the top. The bottom of those 1x2s (facing the ground) were wrapped in reflective, aluminum tape, and the top of the 1x2s have the LED strips facing the ceiling (I can see that the reflective tape does make an appreciable difference). The LED strips themselves are recessed slightly below the black facade pieces to obscure the direct view of the LED spots.

The diffusion panels are just the 4' fluorescent type light covers (got them for about $2 each at the time as they were closing out that particular panel). The black facade bits (painted gloss black) were a combination of wood strips (the upper three may have been pre-painted white at the store), and the bottom and sides were jigsawed out of some sort of compressed fiber/wood panel (rather hard material--again, it's been a fair while since I built it and it was all from scratch on a whim, so some material details are foggy as I just went through the store and found stuff that would make my idea work [my girlfriend thought I was insane as she couldn't envision what I was describing, but she was impressed with the end result ]). The light panels and facade pieces were adhered with some combination of liquid nails (or caulk) and tacks/short nails.

The 3 separate LED strips are set to color change with slightly different timing. This creates a rather mesmerizing effect as it's fairly unpredictable, and when it happens to match all three colors, the room gets a noticeable burst of that color.

Note: All dimensions were determined by the height of the pins and the ceiling height/room size.

lightwalloff (resized).jpg

Took this shot recently as well:

20180424_183711 (resized).jpg

Between whatever is formulating here and your pool project, you're undoubtedly generating a lot of jealousy on Pinside I look forward to the end results.