My tunnel is horribly ugly, so I'm glad it's covered in paint and carpet, lol. I basically just rounded a flat piece of sheet metal I got from a guy at work over my leg into something that looked roughly like a section of a cone. I don't have metal fab skills like that or the equipment to do it real nice, so I just made it work with what I had. Seems to at least have held up fine after nearly 10 years or something though.