Solid color object in base?

[Shenanigunner]

Does anyone know how to get a wall or equivalent of solid color in a base? Say, a wall or other vertical flat object that's colored bright red or blue or whatever?

I did a search of all the tintable objects, but everything wall-like-ish can only be, as the label puts it "tinted" slightly with designated colors.

Am I missing some item or trick?