Either just a thematic piece or an undead-spawning scenario focus
An effective technique is to cut out shapes of thin cardboard. Once painted they will look like more 3-d then they actually are.
I modelled this way: a door frame, a tympanum and door knobs
You can get more quality out of green stuff but I can't sculpt so I settled on simple shape with thin parallel lines from top to bottom pressed with a knife.
Tip: use styrofoam splinters to fill larger volumes. The construction will be more sturdy and you will use less putty.
You can also use sheets of textured paper from a railway model shop