I've made up metal control panels plenty of times, both as replacements and as new designs. If you have an old panel, that is all you need for a plan/template.
I've also simply drawn up plans + pics on a bit of cardboard, no software required, just make sure your measurements are correct. You definitely do not need a CNC or any fancy software.
You want to find your local metal workshop that can bend and cut sheet metal. You may have to ask around, but every major urban centre should have at least one.
Keep in mind that metal workshops like this can do simple cutting and bending of metal sheet, but may not be capable of doing anything small or fussy.
This is usually surprising cheap. In Australia I've gotten new metal control panels done for ~US$60-$80. Metal (especially steel) prices have risen since then, but most of the cost was in the labour. When I've gotten control panels made up in Thailand, the cost has been more like US$15 for a control panel and 8 metal L brackets!! It should not be expensive (unless you want them to cut holes too).
#TIP: The cut metal edges can be sharp!! Go over them all with an angle grinder, file and/or some coarse sandpaper to avoid injury. Also make sure to clean-up any sharp edges on holes you might cut.
#TIP: Metal sheet from the shop will likely have a coating of oil to prevent rust. Wipe off the excess.
If you want the metal shop to cut joy/button holes as well, that will be expensive. You want to avoid this if you can.
I suggest that you try to cut the holes yourself with a holesaw (rated for cutting steel). Use them with your everyday drill. You can buy holesaws as sets (many different sizes), but mostly you only need 2-3 sizes for arcade cabs (28mm for most "fat" buttons, maybe a smaller one like 19mm for Sanwa-type joysticks with a short throw).
#TIP: When using holesaws, drill the centre guide hole first with a separate matching bit (usually 6mm or 1/4"). Use some scrap wood for backing as you drill (to minimise "blowout" on exit, and also to prevent drilling into your workbench).
You do need to make sure your drill bits are rated for cutting steel. Rated for aluminium is not enough!.
As Scott suggested above, have a look at the slagcoin templates. If you print them to the right size you can overlay the pattern onto your metal CP for marking the holes.
Marking metal panels (for drilling holes) is difficult, as it is hard to see the pencil/pen marks. Use masking // paper // painters tape tape on the surface so you can see the lines
This also makes it easier to keep the drill bit from wobbling around while drilling the guide hole.
#TIP: Hammer a nail or pointy screw onto the exact spot for drilling, as this will give the bit something to grab onto and help prevent it from wobbling/wandering at the start.
Check this thread where I am detailing a build of mine with metal CP:
http://forum.arcadecontrols.com/index.php/topic,166352.0.html