You can easily build a machine with a mini rambo from Ryan, series wiring harness and a kit. That will definitely move like a cnc. The lcd Ryan sells has an sd card for printing without a computer. All of that is pretty standard and will go together “easily”.
Attaching a plasma torch to it will require some kind of mount. I don’t do plasma cutting but I guess you want to do some judo while cutting like be at a higher distance to pierce and then bring it down to cut. So there will be some tricks when setting up your toolpaths in CAM for that kind of stuff.
The torch is pretty light and there is no load, but you’ll want the cables to have no resistance when the machine is pulling them. A 5x2’ would probably work. If you’d like to cut wood sometimes, you might instead consider a 2’ wide low rider instead, which would be very rigid. You lose about a foot in each direction to the machine. So if your table is two feet wide, it will end up only one foot wide workspace. There are online calculators for both machines.
The plasma addition is not very common (there are 5-10 posts about it) and not completely explored. Dui’s machine had a ton of emi problems, including smoking a few arduinos. He did manage to get it working with enough shielding on the electronics. I haven’t seen that again. It might be that his plasma torch is especially noisy and others are not. The emi, the mount for the torch, and the cable management are what I would suspect are the biggest risks. But you’ll have to decide if you want to go exploring it.
@Crash85 has just been building one. Maybe he has more input: