War Torn worlds have added the Adventure Crate Set to their online store.
From their website:
You are buying 6 square crates, 6 long crates and 8 chests. I have a license deal with Hirst Arts Fantasy Architecture to make items from his molds and that’s what you have here. He really did a good job on this sculpt.
They are cast with Hydrocal White to which a various shades of brown pigment are added, dipped in an ink was and then a sealer. Try HirstArts.com for painting instructions he has some great samples.