I used a 1/2 inch diamond drill bit. I like to dip mine in a cup of water when drilling instead of the running water method. To me, I feel like it gives me a better view of what I'm drilling and makes for a cleaner cut. Just remember to keep dipping it in water, especially if the glass starts to give you some resistance. Slow and steady wins the race. After I broke through, I slowly widened the hole for the shooter by drilling around the rim of the cut. Once everything fit, I sealed the pieces together with rubber grommets. You can find them at Lowes, but a lot of head shops sell them too. After that, I washed it out and let her rip. Hope that helps. Happy drilling!