How to color and add decals to a union?

In other words from the title, how do I color a union and put a decal on a union. When I try to change the color, nothing happens. When I add a decal, it just fits flat over the box around the union instead of wrapping around the surface. I think I'm missing something obvious, but any help would be nice.

There’s a property in the union called UsePartColor. Check that and you should be able to change the color of the union.

Also decals don’t “wrap” around the surface. They stick on 1 side only. You’ll probably have to add decals on all sides if you want it to wrap the part.