Like others, one of the first modifications I made to my water table was a much larger drain. I decided to use a stainless steel sink drain with removable filter basket to make catching and removing the slag easier, as well as letting the water drain very fast. I’m sure the last 1/8" of water left standing in the bottom of the pan wouldn’t hurt anything, but I really wanted to get it as flush as possible. Due to the size of the drain, a dimple die wouldn’t really be feasible, so I decided to try a pneumatic punch/flange tool.
I was dubious, but after using the plasma cutter to cut the larger drain opening, I purchased a cheap air flange tool from Harbor Freight (this one here), and gave it a shot. To my delight, it actually worked quite well! I made a few passes around with it, trying to ensure a uniform recess, and it did the trick. I applied some Permatex Ultra Copper between the bed and the drain, tightened up the drain nut on the bottom, and it’s been working a treat. I also put a layer of Scotchbrite-type pad in the filter basket to catch the finer sediment, and haven’t noticed it slowing things down yet.
Hopefully someone else will find this helpful, but I’m betting I’ll find some more uses for the flange tool too as I cut thinner sheet metal projects on the Crossfire. Cheers!