These are a bunch of random bits — the back row, far left, is from a Grenadier “Action Art” set, while the back row far right is an idol from the Grenadier AD&D blister “Hill giants”; the two smaller piles in the back row are troll bones from a Warhammer boxed set that included several really cool items of scenery. The dragon skull is from a Grenadier box of swamp monsters, I believe it was the Fantasy Lords or Dragon Lords set that replaced the AD&D swamp monsters set. These are all nice warnings that could be left out by monsters or cultists or whatever, warning adventurers to stay away (or more likely luring them in).
When I got a recast of the Minifigs skeleton cart, I was really conflicted about whether to use the bone pile or the coffin as the cargo, and hit on the idea of making an extra copy of each out of Sculpey. In the end I made a lot of coffins loosely based on the original, both open and closed, and also some copies of the skeleton that goes in the coffin, as well as piles of bones. The copies came out pretty poorly, which is fine, since my goal was just to get something useful for placing on a battlemat when the adventurers happen to be in a crypt, tomb, or catacomb.
I already posted some completely scratch-built sarcophagi, but my favorite one is the plastic model from HeroQuest, which I painted to help bring out the details:
They can lay on top of the stone coffins above, or sit on the floor as crypt-covers. My duplication process (which is just pressing the object into one lump of Sculpey, then baking it, and then using that as a “press mold” for more copies) leaves some detail out, which gives a nice wear & tear effect.