Get a discarded one from a repair garage.
Even if it’s not too grubby you will never get it clean enough to paint.
With the idea of a brake drum for a gong, the imagination can run wild.
A Depot Hack has a place to fasten it externally which makes it handy to ring. On metal cars it would have to be fastened somewhere underneath and you would have to come up with some imagination to transfer the ringing action to the drum.
I am clanging it with a piece of wood to keep it from being so loud in the neighborhood or up close to someone. I wouldn’t want to scare the begeebees out of anyone, would I?
MY picture is looking down on the brake drum.
Gene
Funny you should mention that. I'm a drummer in a church's music ministry and, to simulate the sound of a church bell, purchased a Latin Percussion-brand "ice-bell." Unfortunately, the silly thing sounds like the bell you hear ringside at a prize fight—not very churchy. By taking apart a rear wheel for rebuilding, I discovered that a Rocky Mountain brake drum, when struck, sounds just like a church bell!