For his home Christmas light display this year, Bob Clagett made a pair of giant lightsabers. The hilts are made of cardboard cylinders painted silver and accented with duct tape. The blades are made of clear plastic roofing material and fixed inside the hilts with drywall screws driven through 2x4s. The actual light comes from Christmas decorative lights mounted just inside the hilts.
Clagett found the lightsabers surprisingly sturdy. You can even duel with them!