I have been tying those tube flies on small dia. teflon tubing. I like to add a small amount of crystal flash (4 to 5 strands doubled over) to them for that extra color. I have tied them in a number of colors, some in two colors. Remember the rags that Bob had on the daily reports on day. Try contrasting patterns. Black and white, pink and black, also match shrimp and egg colors for no bait rivers. You can fish these either above or below a corkey or egg type drifter. When fished above it gives a larger profile plus the marabou looks more life like. Best of luck.