Hi Neil,

Those tools are more than enough in the right hands.
Regards the box 50x50 3mm wall is Ideal and cost affective.

The size of machine you want I started to design for a guy a year or so ago and to do pritty much the same panel work. The budget was tight on this as well but didn't want to build weak.
It was decided steel frame and R&P was the best way to go. Often most designs requires driving the X (or long) axis from both sides and this means extra expense, 2 motors, 2 drives,larger power supply etc.
So I started designing so I could build it with just 1 larger motor on the long Axis 3:1 ratio giving roughly a 25mm pitch thou can be changed with differant sized pulleys and/or pinion.! . . . The pics below are as far as I got. (As folks are probably gathering by now I like my pics.!!. . . They tell a thousand words. :tup:)

It's just a rough layout design and still needs plenty more work but the frame etc are all to scale thou a little extra strengthening to the bed and some bracing are still required. The dimensions are 3mtr x 1.5 which is more than enough for 8x4 sheets.
It never got built due to the guy being made redundent and it's currently on hold untill another day, hence I stopped designing.
If you want to know more drop me a PM and I'll give ya my number.

Also digging this out got me thinking how much the steel would be for this frame and If it could be built for £1000.???
So I rung my supplier and got a price for 50x50x3 7.5mtr lengths of £25+Vat . . . I've worked out 6 lengths lengths of box section should be more than enough. . . so £150 will build you the base frame and gantry.
Commercial Rack is roughly £30 for 2mtr lengths so £120 for X&Y axis, pinions £8 x 3 shaft say roughly £20, Bearings and pulleys approx £50 so R&P for X&Y Axis approx £220-50.

Throw in roughly another £300 for linear rails and you still havent got Z axis or motors, drives, PSU etc . . . so what I'm saying is on reflection then £1500 is more than likely your finished price. thou for £1500 you'll have a cracking machine.