I used C9 transparent bulbs. You could use C7 bulbs but they are smaller. I chose transparent bulbs because I thought they would show the light from inside better. The bulbs do not need to work. I picked up most of my bulbs at local second hand store.
Step 2: Glass glue
I was worried about this step but I used Duco Cement and it worked great. It dries stiff (not set) in about 15 minutes. Build the layers around the inside of the cone a little at a time. (If I build another I will add pics)
Step 3: Light up the lights
I inserted a string of white lights inside the cone but I think it looks just as great unlit.