When the fireplace is not being used, ie 360 days per year, we have a slice of hardboard covering the dark maw, keeps the draughts out and the dust down.
I'm making a little applique front for it.
It won't be anywhere near the fireplace when the fireplace has heat, so flammability is not a problem.
I'm making a peacock design from odds and sods in the stash. Paisley works well as feathers.
I'm having fun.