To make the rectangular hole in the tub and to make the holes for the zip ties, I just used a box cutter. It was a lot easier than it sounds and it doesn't look bad at all! (I was very careful to make a straight line for the rectangle part and the holes were really easy to make!)

This also worked when I put some holes in my snake tubs and I haven’t had to replace my razor yet! I know it sounds ridiculous but it sure saved me money on a drill.