We've got one made by SIP. The main change to the original spec is that we use a bottle of ArgoShield Lite which we rent from British Gas rather than the little £10-15 disposable cylinders it's designed to run with. If you're serious about welding this is an excellent investment. The up front cost is a regulator (which cost about £35, from Turner Engineering of Bar Hill) and the bottle rental (about £20 pa). Each fill costs about £20 and a bottle lasts forever - we're still on our first one after a year. Before that we were getting through disposables all the time. We estimate that we've saved the capital costs in the first year so we're into profit now. Argoshield is also a lot better than C02 for welding with.
We've also built a trolley which holds the welder and the bottle and makes it a lot easier to move it around.
For welding big bits of metal, or when it's windy you still can't beat an arc welder.
We've got a Bosch power drill. Reversible, variable speed, two speed gearbox, keyless chuck. The chuck is a real boon as is the variable speed control. You can "dial in" the top speed and then lock the trigger at that speed which makes it a lot easier when you're using a wire brush head (which we did a lot). Wire brush heads, both the cup and wheel type are extremely useful. The other thing we've found useful is a "flap wheel". Good for getting back to bright metal.
Another Bosch job. Ideal for getting screws and bolts in and out. We've got a 1/4" hex drive to 1/2" socket converter which lets us spin small sockets.
Absolutely vital. We have two. A standard 4.5" one and a BFO 9" one. The latter is unwieldy, noisy and a lot more difficult to handle but it's well worth it, especially for cutting. It's this that will chop the old chassis up when we get around to dumping it.
By the way it's worth having both cutting and grinding discs. Don't try using one for all.
Although the angle grinders will cut most things an alligator saw has two advantages: it doesn't shower the environment with sparks and it can get into places an angle grinder disc simply can't. For example Paul cut a bolt through by sliding the blade between the two plates it was holding together. Also proved excellent for carving bits out of footwells.
Be warned though - the blades are expensive and break easily. Goggles are vital!
Beth has a set of Sealey wall drive sockets. These avoid rounding of nuts and are well worth the money. Quite excellent.
Paul has a set of Metrinch spanners, which again avoid rounding nuts and he wouldn't be without.
These cost about £10 for a hundred and are the same sort of thing surgeons use, only not sterile. They're becoming the norm now among pros because of the cancer risks from oil. For Paul there's two reasons to use them: firstly because your hands stay relatively clean (but see below) but the second and more important reason is that they give you some protection from scratches and cuts, which you otherwise get a lot of as your struggle to release rusty nuts and bolts.
Much better than Swarfega.