haha you beat me to it.i was gonna say glass holes also.i just bought their dart overflow box and 2 return kits.reasonable prices and super fast shipping.
I just bought the glass holes 1500gph kit myself. fairly straightforward, they have videos on their site. I was worried about cracking the glass but it went smoothly. if you buy their returns, also get yourself a 1.5" holesaw for wood because they didn't give me a template for the return. you can use the holesaw to drill a 1.5" hole in the template they give you for the drains.