I think I'd just get a piece of 3/8" aluminum plate, rivet some suitable
handles on the sides. The advantage of the aluminum is that it has very
high heat conductivity, the entire plate will be at the (almost) same temp.

A stainless plate would need to be very thick to avoid warping:
stainless is a fairly poor heat conductor, the areas over the burners
will expand while the outside edge stays much cooler. That will make the
center dish up/down, not fun for fried food prep.

wrote:
I've a gas stovetop and want to make portable a griddle- ?stainless,
steel, cast, to lay on top of the burners when I want to make giant
amounts of fried food. I thought I'd get approx 1/4 inch thick
material and weld handles on the sides. Do not want a lip. Obviously
my main concern is food safety. Also concerned about warping with heat
applied and cracking. My stove came with a nice cast aluminum griddle
but its too small- only covers 2 burners. Don't care if it's heavy.

Thanks for any thoughts.

Dale