Slightly off on a tangent...
Water Machining is simply OUTRAGEOUS!
I've seen 'em cut through 3" steel. It's very slow but very clean. Like most things, the greater the load, the more it takes... in either power, or time, or both. The thinner the work, and the softer the material, the faster.
Those machines are spendy as hell. The nozzle replacement rate on the abrasive type systems is much higher than that on the water-only systems. I've heard numbers like 65,000 psi!
I would love to have an X-Y head with a water-cutter. One of my distractions is Stained Glass. I would love to use a water-cutter instead of a handheld glass-cutter for intricate shapes.
There is a trick we use for blowing a circle in the middle of a piece of glass (it works best with flat-glass... not so good with textured glass). Make a small score at the circumference of the circle (only a couple of degrees of arc). Then, using the tap-ball on the other end of the glass-gutter, apply a short, sharp tap at the center of the circle. If all works out well, then, when the vibration of the tap radiates out from the tap-point to the score mark, the glass fractures. The fracture line produces a circle about the center-point with a very consistent radius.
If all goes well, then the circle simply falls out of the pane. If that occurs, then there is a very satisfied "Aaaaahhhh!". You then have a piece that can be developed beautifully with copper foil; lead-came doesn't work real well in these cases, especially if the project is an external window.
If the circle doesn't drop out as expected, then sometimes a few small taps in a few strategic places might complete the fracture (not often). Otherwise, it's simply another piece of glass for the "small-piece" bin.
You might have seen one of those Secret Agent or Professional Burglar movies where they apply a suction cup and use a circumscribe to score a circle. They then simply pull the circle of glass out of the pane.
I've seen only a very few where they show the "secret step". The secret step is a triggered hammer at the center of the suction cup that strikes the glass at the center of the circle. This produces the vibration that radiates out to the score mark.
I've considered doing this with a laser... too hot; the glass would "craze".
Water Machining would eliminate the heat issue and allow the production of any number of non-circular openings in a pane. Imagine, a non-circular cut in the middle of any kind of glass, flat or textured. And a beautiful, square, or rectangular, or oval, or some weird irregular shaped Stained Glass work-piece inserted in the middle of that glass!
Damn... if only they were affordable... I could consider leaving PLC's... naaaahhh, I'll never leave PLC's!
After all, I would probably want a PLC so that I could contol every aspect of the X-Y tooling!
In terms of panels, since water-machining is out of reach for most, I believe that a plasma cutter is great! We have a few guys here that love to get "artsy" with a plasma cutter... moose, elk, reindeer, the boss with his pants down, etc.
Of course, use it on a raw panel, not a painted one. Get your panel cut to the rough finish, grind it to the final finish, punch your holes and then send it out for paint.