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.
Stuck inside because of the weather? This DIY Nerf spinning target game is a simple and fun way to keep kids entertained all day, whether they are crafting or playing the game. Click in for the complete tutorial from Frugal Fun for Boys and Girls.