Ralph, thanks for the useful information. I am beginning to see the benefits of your card timber solution.
I have received my trial lasercuts, and have attached photos:-
Timbers-and-Jig
Trackbed
I have also attached the box file from which the dfx was derived
For trial purposes I used 3.2mm ply for the trackbed rather than cork, as the cork was not available in this sheet size. from my supplier.
The idea being that the trackbed just has sockets, which use temporary locator plugs to locate the timbers.
I included a straight B7 turnout and a curved B7 turnout.
I know the experimental chairs option is not ready yet for turnouts, but I beleive I have learnt something from this trial.
The sockets on the turnout timbers on the exit stock rail are gardually angled in respect of the timber, and that makes these timbers asymetrical so when using them it will be necessary to take great care that they are they right way round and the right way up.
A bit like taking care to ensure your bullhead rail is the right way up!
So I can see that 3D printing turnout timbers with flanges and connecting webs as Martin has demonstrated is probably a better solution than ply timbers as you can't go wrong with the orientation or seuquence of the timbers.
Back to the ply trial.
Turnouts
Another thought occured to me that pending the whole gamut of turnout chairs, one could use a hybrid approach, and use the plug-track approach for those timbers that that use S1 chairs, and other means for the other timbers. For example copper clad timbers and etched chairs for the Slide chair timbers, Pre-constructed croosing vees and cosmetic chairs etc. Plastic chairs glued to ply timbers etc.
Having output the DFX file it is relatively easy to delete the unwanted non S! sockets.