Another Newbie

[m_c]

There are precision nozzles available for the better brands of plasma cutters, however it all depends on how much you want to spend.
Hypertherm is one of the top end brands that I can think of right now that I think does them.

[Chris J]

There are precision nozzles available for the better brands of plasma cutters, however it all depends on how much you want to spend.
Hypertherm is one of the top end brands that I can think of right now that I think does them.

The minute someone says it depends on how much you want to spend my blood chills a bit

I guess I was hoping to spend £1k maybe a bit more, not including a pc, so not a huge budget.

[m_c]

The minute someone says it depends on how much you want to spend my blood chills a bit

I think it has that effect on most people!
If only I could match those 6 numbers...

I guess I was hoping to spend £1k maybe a bit more, not including a pc, so not a huge budget.

As Ian's highlighted HiDef plasma is out of the budget.
I know normal plasma has a cut width of 2-3mm, and would be fine for doing the main outline cutting, so it may be worth considering a router/plasma hybrid. The two processes do have opposing requirements for cnc, but given your requirements, and with some careful design, should be doable.
Under typical use, a plasma table requires lots of speed with little torque and not very tight tolerances (when you've got something cutting +-0.5mm/trailing behind the torch position, tolerances/backlash requirements aren't that high), whereas a router table needs more torque with less speed but tighter tolerances.
However, given the size of cutters you need, torque won't have to be much for the router, and with the reasonable price of ballscrews, a good compromise of torque, speed, and tolerances should be doable, and combined with a lower power plasma cutter you shouldn't need crazy high cutting speeds.

[Jonathan]

I think you'd be best to design a CNC router than can incorporate a plasma cutter, but don't get the plasma cutter until you've tried cutting with the CNC router. I'm fairly confident that with plenty of coolant you'll be able to cut the copper without problems. When I cut that part from 5mm copper the part got exceptionally hot, but with flood coolant that wont be a problem.

[Chris J]

Ah coolant, I hadn't thought of that.

I guess that means I could't have any board involved.
I had thought I might clamp the working sheet to a sacrificial piece of board.

Mmmm, there is always something

[JAZZCNC]

Ah coolant, I hadn't thought of that.

I guess that means I could't have any board involved.
I had thought I might clamp the working sheet to a sacrificial piece of board.

Mmmm, there is always something

Not a problem just use plastic sacrifical board, hdpe is what I use very flat and stable? . . .BUT a far bigger problem you will have with small items like this is the actual clamping and holding.? Unless they have holes for screwing or clamping thru then it's a night mare holding small items for profiling.!
The thinner the material the worse the problem, I often spend more time making holding fixtures, jigs or repositioning clamps etc than the actual parts take to machine. IE: Recently machined some small Brass items and the total Job time was 30 minutes per 4 buckles the machining time was 17mins the rest was made up having to swap clamp positions without disturbing position and 1 tool change(2mins max).

[mocha]

I can see myself trying this sort of job... Would tabs solve the problem Jazz??

[Chris J]

I wonder if some kind of picture frame might work.
Slide the sheet in, make the cuts.

[JAZZCNC]

I can see myself trying this sort of job... Would tabs solve the problem Jazz??

Yes they work for some jobs but not all and with really thin material or small parts then there's not much left for the tab and they break or let the part lift.

On small parts I often leave a thin skin 0.1-0.2mm and don't actually cut right thru so it's kind of like a one big tab then just clean up with de-burr tool or quick blast across the sander and the skins gone, tabs on small parts don't really work very well.!

I wonder if some kind of picture frame might work.
Slide the sheet in, make the cuts.

Chris the problem comes from when you do the profile or outside cut thru the material, if not held down it will get grabbed or flung by the cutting tool. No sicker feeling than seeing a beautiful part which took 2 hours machine time come to life only to get chewed up and spit out in 2secs.!!

Clamping is probably one of the most un-thought about and time consuming things in DIY CNC.!! Unfortunatly the smaller the parts or thinner the material the worse the issue the more the need to get a good system in place.
If you have any thoughts to make multple identical parts then it's often worth taking the time to make a dedicated Jigs.!

[mocha]

Yes they work for some jobs but not all and with really thin material or small parts then there's not much left for the tab and they break or let the part lift.

On small parts I often leave a thin skin 0.1-0.2mm and don't actually cut right thru so it's kind of like a one big tab then just clean up with de-burr tool or quick blast across the sander and the skins gone, tabs on small parts don't really work very well.!

Thanks Jazz, I was thinking, using the OP question as the example, leaving 4 tabs of completely uncut material... then cutting through them with a fret saw, but yes, take your point.