Once it cooled, I got ready to add the lights. Rather than using Christmas lights, I used Floral lights from Michaels. The are smaller and not as bright, but I have always prefered a dark, ominous look to my dios!
I drilled holes through the top and secured the lights with duct tape. Almost exactly as ViolentFX suggested.
I didn't understand what he was talking about when he used "Conduit" to cover the slot on the side of his tunnel. I bought 2 - 12' pieces of 1inch diameter PVC pipe and spray painted it black and gray to give it a used appearance. Then I taped it together using duct tape and slid it down the tunnel:
It kept falling to the bottom, so using wire and scrap wood, I fixed it in place;
Viola! Just turn on the lights inside and poof! Instant tunnel. If you need a side shot, loosen the PVC pipe, pull it out and take the pic......