It's worth mentioning that an angle grinder can be had for a mere 15 bucks at a discount (read: Made In China, cheap quality) tool supply (like Harbor Freight, aka Horror Fright)...and flap wheels are cheap (what you'll want to use for anything other than steel)...that's probably the most often-used hand tool I own, on everything from small tabs and brackets to large assemblies.

Clearcoat your mild steel, to keep the finish. If you don't, it'll corrode over time just sitting in the open air, and heaven forbid you spill beer or something on it (or it happens to rain)...it will be orange in short order. You'll be oiling & polishing the exposed material all the time, which is a pain in the butt...clearcoat is much easier.

4130 takes much longer to corrode, but it's more expensive, good luck finding scrap...the saying goes "there's no such thing as scrap 4130".

If you're interested in steel (or other hard metal) buttons, take a look at Jancy Engineering's "Slugger" sheetmetal cutters, the small sizes use a non-penetrating, spring loaded center (vs the 1/4" pilot of the larger cutters), and the drop is a very clean circle of material. Drill the holes for thread, clean the piece, and you have a button from the metal of your choice. If someone were enterprising and had a good CNC mill, it would be easier to make a bunch of them at once, and they could even be engraved in the process. Polished brass, coarse-cut aluminum, or brushed stainless surfaces would look great, I bet.

The cantle I have in mind is just mild steel, grinder-polished, maybe run a bead around the outside edge for appearance, hit the entire piece with a wire wheel, and clearcoat it.

As a matter of fact, that just sparked an interesting idea. I usually make my practice welds on straight tickets, now if I did the same thing on a curved ticket of 1/8", laying the appropriate beads, I'd end up with a roughly 1/4" thick cantle that looked like scales, and since the beads would be running around rather than across the cantle, there'd be much less concern about the piece warping funny. I think I'm going to try this...1/8" is easy to cut.

If only I had a set of dimple dies...it would be pretty funny if my excuse to buy a set were to make go-fast holes in a cantle .

-Sean