A real acid bath would be laggy. Maybe an acid shower instead?

Dude, .lua acid bath is easy to make.
Just make a box, make it that any actors that fell in get their health reduced to 0.
Add special effects if you like...

That's exactly what I mean its like the kill zone in map pack 3, but it should be a wide bunker piece with sliding doors that cover the acid to keep friendly units safe.

Real as in actual acid particles, not faked up with Lua.
Anyway, as carrion said, a fake one is trivial.

I only care if its effective. How you make it work is up to you. If it has a tractor beam to suck in actors or a door that locks a room then slowly push's the enemy actors into acid then Id call you a god at trap making.