I was going to use this super plush flooring sample. I have enough of them to cover the floor! But I couldn't get them to lie flat... they had a bit of a curve, and I couldn't get the edges to match so that it looked like seamless carpeting.
Do you know what makes perfect dollhouse carpeting? Upholstery fabric! I got a few squares in different colors and patterns from a garage sale, and I attached it to a posterboard backing. Tada! A floor for my Gentleman Velociraptor to stand on!