i cut the hole 1/8" smaller than OD. of the dome then i take a router and a 90% cutting bit (it takes out 3/16")
then i take out about half of whats the material thickness is.
so if your using 1/2" ply i take out 1/4"
http://i91.photobucket.com/albums/k3...c/IMG00184.jpg
for you that wanna know how i cover my whole for my dome lamp this is how
wire mesh that can stand very high heat glued down with hot glue haha it works and the glue doesn't get sticky with all that heat. Cause i just checked the hot glue gun and the temps get around 160+ and, well my domes never ever get over 130ish
http://i91.photobucket.com/albums/k3...c/IMG00207.jpg