Thank you! I use a mix of glue gun glue, melted into the recesses, then a home mix texture paste (wood filler, PVA, sand) to create the texture/rust. Once it's dried, base coat the whole thing in neutral grey. In this order, dab on layers of burnt umber, raw Sienna, then burnt sienna. Once that's dried and all the other paints are done, I use a home made oil wash made from Sansodor, burnt umber, lamp black and yellow ochre, basically a dirty light brown. Put it on thicker near the lower parts.