I pick up vintage faucet handles whenever I find them at flea markets. I have way too many to use on my own projects so I'm passing them along to you.

Most are "normal" garden faucet size. But I do have a couple of larger ones listed right now.

Medium red: 3 1/2" across measured from the little bumps on the outside. This one is cast iron and heavier.

Large red: 5" -- Says "open" on the bottom.