If you're building the tank yourself, probably best to drill the holes before assembling the glass sheets. Definitely need to have a drill press in order to keep the drill in position and perfectly level; it will wander everywhere to start with if hand holding. As you say, take it very slow and steady. Build a dam around the hole site with plasticine, putty, etc and fill will appropriate cutting fluid / lubricant. maybe just water with a bit of washing up liquid.
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.