Hi Rebel, welcome to the Planted Tank, the answer to all your moss wall questions! :mrgreen:
I found myself pondering about mosses that are not green colored. Honestly, I am still pondering, but I think so far every moss I came across displayed some shade of green.
So anyway... Moss walls, great idea! I have one in my 10 gal. I went to Walmart, and bought some of those plastic grids, that are used for some kind of cross stitching or something, they are about 25 cents.
Took two of them, and spaced some Javamoss in between, and put it in the tank. It turned into a moss wall pretty quickly, although I have to say that Christmas Moos (which I acquired later on) would make a much better moss wall, due to the more compact and thick growth (and the Christmas ornaments, if you will).
I think moss walls are the coolest background for a small tank! Maybe for a bigger one too, but I suppose you'd have to feed the moss, it would probably eat quite a bit of nitrates.
Sorry, no red or blue moss walls came to my mind. But definitely get some Christmas moss, and once it has grown in, share some pictures!