First lets cover the list of material.

1 115G Oceanic Tank 48 x 18 x 30
1 Dremel (I have the digital kind with 35 speed setting but they all work)
3 diamond bits (pictured below, ebay special,Ebay Link to Diamond Bits)
water hose
duct tape

Ok here is the tank being marked up. We put 2 holes in the top for the overflows and one near the bottom for the closed loop intake (not pictured).


Then took it to the grass. Traced around the bulkhead just to make sure and put duct tape on the bottom. I read on RC it helps it not crack!




Then the actual process. Here are the bits used.


We used the ball to start the process and drill about 2/3rds to 3/4ths of the way through. This guy takes off some major glass and works great but is to big and thick to risk punching though the glass. Notice the water is constantly running on the hole. This keeps everything cool and washes away the glass dust!


After that is 3/4ths through the glass then we take the sharp pointed bit and drill straight through. This is the most nerve racking part because if it is going to crack it's going to do it when you breakthorugh to the other side! Once there was a hole all the way through big enough we take the cylinder bit and go around the hole mark in a slow up and down motion.






Then eventually you make a circle and your done. Do note to put a towel or something under the hole to catch the glass when it falls. It would suck to get through the hole and break the tank with the falling glass! Here is a picture with 2 of them completely finished.


Here it is done and back on the stand!!




The first one took us about 40 minutes as we were really careful. Once we got the hang of it though the last one only took about 15. It was cool and I'm glad I got a chance to try it. Hopefully this will help you out if you ever decide to do it! (Kieth (kwl1763 on DFWMAS.org)

References
DWFMAS.org DIY Forum: Drilled a 115 with dremel