Always wanted a wood-rim steering wheel in my 3500s but didn't really like the thin original optional wheel, I did however want to keep the original two spoke design. Final conclusion was to build my own.
Really pleased with it and reduced it to 15" whilst I was at it.
I haven't put the finger mouldings on the back, I have PAS so didn't feel the need. It would be possible but very labour intensive without some form of jig to get even depth and spacing. I note your concern about the potential for it to be slippery but many of the aftermarket Motalita stuff is totally smooth as well plus this rim is a lot thicker which gives far greater purchase.
In the event of an accident I suspect the wheel will deform in a very similar fashion as the wood is not very thick and the spokes should deform in exactly the same way. If however the wheel rim does prove to be more sturdy all it will do is spread the impact load over the whole chest rather than a direct hit on the sternum from the centre boss. Don't watch this space as I don't have any intention of testing my beliefs.
Thanks, I know that there are 2 different 'camps' of thin or thicker rims. I'm sure it would be possible to do a thin rim similar to mine but it would just take a lot more care with smaller tolerances etc.