Off to the Birkett tomorrow.
I wanted to go back with a shoulder rig after last year - I'd heard a lot about them at the Canon show last autumn and it was clear they were probably a great tool. The problem was that a good rig would cost over £500 to buy, or at least £50 to hire, so I made some enquiries around some cameramen I know.
As a result I went round to a friend's a few nights ago to borrow his home-made rig to get some more stable footage this year. This was his rig:

Which is simple - it's one half of a ladder hanging rack, with a shelf bracket to go into your shoulder. There's a trick proper foot for the camera and some pipe lagging covered in gaffer tape, to give a bit of comfort.
The problem was I knew what I wanted - I wanted a proper over-the shoulder, counter-balanced rig that meant I wouldn't have to support the whole weight of the camera in front of me. His rig also lacked a pistol grip and because the front bar stuck out in front of the camera, to the side of it, the camera wanted to pull across to the side the whole time - not going to be comfortable for a whole day running around a racetrack.
The key thing about the rig was that it gave me a clear idea about the ergonomics that were needed.
So I bought a couple of bits and 5' of 25mm thin wall tube and borrowed a tube-bender from another mate.
Quick release camera mount: £25

A couple of stainless U-clamps from a chandlery - £16! OUCH!
To start I bent two sections of tube - one slightly more than 90 degrees, the other, slightly less. I then jubilee-clamped them together. After a little playing it felt about right.
Then I had a hunt around for some steel box to make the camera bearer. I eventually came up trumps with a bit of steel on a trolley in the workshop, which had been made up from a couple of big TV stands!
Then I found the clamps were slightly too big - no problem - I cut off a couple of pieces of fuel hose and wound them down round the Us to space the clamps - done!
Then I bent the remaining bit of tube and cut it off at an angle, then profiled it a bit, to mate up with the straight bit - this would be the pistol grip, which is off at an angle in front of the camera mount, to balance the rig up side to side.
I then cut down some plate into a rough circle, drilled a hole in it, welded a bolt into it and drilled two holes in the main bar.
Once it was assembled and seemed comfortable I then welded the two starting bits of tube together.
Then the bits were roughed up a bit and sprayed (badly) with etch primer.
Once that was done I went a hooked a handlebar grip off a bike of mine and eased that up the pistol grip. Then a leftover bit of cage padding got zip-tied and gaffer taped to the vertical chest piece. Then I went and cut off a bit of lead flashing that is waiting to be recycled and gaffer taped this to the end of the shoulder mount.
This gave a rig that was nearly front-to back balanced and when held with the pistol grip wants to sit upright on your shoulder!

Now it may need a bit of padding on the shoulder bar, but we'll see how we do tomorrow and Saturday - a bit of rag with some gaffer tape should sort things if it gets too painful!
Pleased with the result so far, the acid test comes on Saturday when I spend most of a day with it on my shoulder!