preserving dead wood

[minnie pal]

I managed to get some cut down tree trunks of varying sizes for bird tables and feeder posts, but i would like to preserve the wood.
I dont want anything that will take from the natural colour, nor harm animals around either.
I also deshredded a bush of leaves about a few weeks ago and the structure left is amazing, the birds use it as a perch. I have dug it up too and want to keep the skeleton, that too needs preserving.
Finally tall twisted thick branches i want to paint. can i paint some with hammerite blue metallic to go with the iron chairs i found in a skip?
I want to make a sculpture of these branches.
any advice graciously received.
minnie pal