I'll have to try that on my grille, if I can find a big enough tub!
Couldn't a wooden frame be made, then put some sort of heavy plastic sheeting fastened to it to make a trough?
Todjob2000, thanks for the tip on the Eagle One. That made me remember that I used some of that many years ago on some Mach 8 Cragar aluminum rims, I swear it is uncut muratic acid. Followed up with polishing compound and then buffing compound. A lot of work but they ended up looking like new.