For some time now I have wanted to make a Dragon / Wyrm thing and have it be hollow so smoke can pass through it for use as a pipe or part of an elaborate bong.
When I made the base for this one using a processing program to create a height map and then generate an OpenSCAD polyhedron of it, the result looked like sand dunes. This reminded me of Dune the novel series, of which I have read one book and enjoyed it fairly well.
Now I am one to go for the spice that these Dune Wyrms produce, so it is not yet determined as to whether it is printable or not. I plan to print a small one just to see if it needs any supports. At any rate, it's a work in progress so take it with a grain of salt (and some spice).

You construct the Wyrm and the Surface separately. The Wyrm is generated with an OpenSCAD file Wyrm.scad and the Surface is generated by the Processing program SurfaceMaker.pde which generates SurfaceMaker.scad that produces SurfaceMaker.stl. Of course Wyrm.scad produces Wyrm.stl, then Scene.scad combines the two stl files into a scene.
Everything is watertight and all kosher. You can modify the trig expressions in the Wyrm.scad file to change its wiggling shape and then you kind of test fit it to the sand land you randomly get from SurfaceMaker. Experimentation and trial and error is the key here. Or just use it as-is!