I drilled my frag tank using a drill guide from harbor freight, think it was $16, and diamond hole saws from amazon, $6 each. The drill guide did prevent me from drilling higher but it was ok for me, I guess you could remove the top brace of the tank to go higher. Just marked where I wanted to drill, put painters tape on the inside of the tank that'll cover the hole area, setup the drill guide with a corded drill, placed a garden hose with low water flow on the drill area, turn the drill on and put little to no pressure on the drill, it took about 5min to drill through a 20g long tank.