LightCubesMobile - WIP - Universal tool for design products and services

I wanna make app for designers in Unreal Engine but I’m complete rookie for UE! There is so many options and some of them are hard to read or understand so I need help a bit.

My App:
Have 3d “Tetris like” cubes and wanna make a light-gray room… one invisible 3x3x3 cube… where “Tetris 3d models”/parts can be snapped into that cube and emitting colored light on greyish room walls which is also cube but wider and with rounded edges.

I’ve made all models just need to connect those models and thing to work!.. but I don’t know how to do that. Objects need to get chosen from UI menu, give a certain color from color picker, then to can snap in invisible 3x3x3 cube, then colored cubes need to mix other cubes colors combination and give a resulting overwhelming color as result projected on all 6 sides of cube in fact on walls of world rounded cube, where user will get overwhelming color result and explanation of overwhelming color meaning.

WIP files for UE4: https://www.dropbox.com/s/z981kwbb3wfg6mw/LightCubesMobile.zip?dl=0

bump bump bump

If someone can’t help me I would like to see some tutorials for resolving my case.