As a point of reference, I also did the “dam” with tape around the outside edge of the drain, and then ground a taper with a die grinder after the epoxy set. It seems the epoxxy llikes to climb the tape and leave a ridge.
I relocated my drains and mounted them temporarily using plywood, and then spend a lot of time getting them perfectly level in both the x and y directions, and at the proper level relative to the baseplate. That work paid off, I have no pooling except if the chips pile up and plug the screen. I agree, the design of the drains is not great, there is a lot of room for improvement there.
That being said, I also relocated the drains and put in 3/4" tubing with no right angles before pouring, so the fluid can really get out of the enclosure (I documented that in a seperate thread - Mods thread - I know it’s a bit late for you do to that, you can modify the drains after the fact but you will need to drill out the concrete - a 3/4" hole is not hard to drill with a good concrete impact drill, it will go right through the concrete and the sheet steel. I was thinking this might be a solution, just drill a hole and epoxy a large PCV tube inside the hold in the concrete. I have done this before on construction slab work, should work here,
Cheers,
Mike