Edit: LOL! Kari was faster than I tonight! But I'll leave what I wrote:
Lori, you can get disks from most of the usual suspects, like Thunderbird Supply or Rio Grande. You can see some of the sizes and gauges available at www.thunderbird
I hope someone has "the perfect" hole making solution, and I think the best solution may depend on what size holes you are trying to achieve. I can know of several ways to make them, though. The holes can be drilled, with a little practice. Mark the center of the circle with a dot, indent the dot just a bit by tapping an awl lightly with a hammer, then drill. Depending on the size hole (and corresponding drill bit) you might want a micro attachment for your Dremel--hold those tiny bits more securely. The kerfy edge should go on the "inside" of the cap, and you may or may not have to do some finishing with a round file and whatnot.
There is a manual doohicky which can cut two sizes of holes. It's a small bar (about 3 inches)with a slit on each end, into which you slide the metal. Then you turn a little handle on top which forces a hole cutter through the metal. Rio has one, but they are available other places. Rio calls theirs the "Handy Hole Punch." Just make sure the throat is deep enough and at least one of the two hole sizes will workfor you. Rio's make a 1.88mm and a 2.39 mm. Different brands, though, may have slightly different throat sizes and holes, so check around.
There are also punches, available in sets and some catalogs in singles. You have to be able to deliver a whack straight down for the best hole. The smallest I know of is about 1/8."
I also see that Rio has a pair of hole punching pliers--if a 1.25 mm hole works for you--$28.00
I have a great handtool now made by American Whitney which has a variety of cutting dies which can be screwed in. Works like a charm and cuts like butter, BUT the trick is centering the darn thing, since it's a bit tricky to see what you're doing.
Definitely doable, though!