Sorry if this obvious or has already been discussed I’m quite new to dndbeyond.
I was recently trying to make a golem type race, and I wanted it to be able to change its material. I can’t seem to think of a way to do this that isn’t sub-races made of the different materials, whether it can even be considered a racial trait I’m not sure. I tried to make it as a racial trait but given that it would change stats I just couldn’t work it out.  If anyone can help I just need to know if it’s at all possible and (if it is) how to get started. I should be able to work it out from there. 

Thanks for any help. 

You would need to make them as “variant” races.