DIY Yarn Wrapped Jam Jars - it's a good idea for the tunnel just to light the way. A solid row of these along the sides of the tunnel would be a good alternative to using whatever lights are built into it.
Paper crafts are probably the easiest type of DIY crafts, yet its still a lot of fun. It doesnt require a lot of resources nor high skills, most of the time you only need some papers, scissors, and glue. Enjoy trying these easy and beautiful paper crafts.