The slots can be used to clamp pieces with the same tooling as the mill (and some of our drill presses). in case you’re not familiar:
I don’t remember off the top of my head, but it may be a better value than the guy we were thinking of buying from. They do also have larger tables. The one posted is smallish, but is flat and probably more than enough for what we actually/usually do. a double sized one is ~$800
Ryan and I looked at this. Decided that it was pretty meh for the price. If we are going to go with a sheet metal top those can be found cheaper than buying a miller branded one.
Something like that would be better off modified with a ton of bracing material. And then you need to worry about whether you made it not-flat from welding bracing. Part of the joy of a welding table is being able to brace things to it and use it as a flat surface to build things on. You’d need to do some work to those stainless prep tables to achieve that goal.
-D