I use gesso on my canvas paintings, for something like this I probably would have gone with a terrain paste which is mod podge and grout with a little water and a color paint to tint it (usually grey or brown) if you want a more textured terrain paste add sand. These came out fantastic.
My sister got me some Gesso some months ago as a replacement for primer. it said to water it down before application. For some of my miniatures that are 3d printed with detail, the watered down gesso seems to work fine. On the label it recommends a 3 to 1 (gesso to water) mixture. With that said, yours might already be diluted to that consistency (I'm just running out of the gesso mixture i had made). I also was afraid that the gesso would take away from the printed texture, so i've been only using 1 layer before i painted.
Tip for next time: If you know you want to add lights and wires, just add the channel for the wires inside your 3D model, so your support infill won't be in the way... ;-)
Thanks! I am still learning about supports but I think I can modify something like that next time. I figured out the mapping after I had already printed it. :(
