I don't know if this would be considered an 'odd' request, but, I'm after a
cross section of a large tree !

What I'm specifically looking to do is obtain a disc, about 1"-2" wide, cut
from a tree at least 100 yrs old. I have been asked to source one by an
artist who wishes to burn images relevant to the years shown by the rings.
From what I've found so far I reckon Douglas Fir should do the trick.

http://www.ltrr.arizona.edu/lorim/good.html

I'm told it's called pyrography and it looks 'quite nice' hanging on a stone
fireplace/chimney breast.

My thanks in advance for any possible UK suppliers.