Worms crawling under skin I wanted to create a scene where you can see a worm crawling underneath the skin of a person's belly.

I've tried it with the tools provided in Blender like the deform modifiers (mostly I tried with Cast modifier, warp modifier and partially the displace modifier) but it just doesn't look like a worm.

The cast and warp modifier do not support custom shapes, only the basic sphere, cube and cylinder.

Does anybody know how I can achieve this result? I also tried with softbody physics, but that didn't really work out well when pushing a collision from the inside, especially because the shape didn't really come through.

Is there any way I can get the form of a more abstract shape seen and shaped through another object without using shapekeys?

The whole scene is CG, so it isn't about a real video where I want a CG worm to crawl underneath the skin; its just a CG character.
You could use the Vertex Weigh Proximity modifier to control displacement.
It will use the actual shape of the mesh to correctly displace the surface.



Create a new vertex group in your "skin" mesh and add all vertex to it with a strength of $1$. Now add a new Vertex Weigh Proximity modifier, pick that vertex group, set the "Worm" mesh as Target Object and make sure to set the Distance Mode to Geometry.



After that add a Displacement modifier with weight affected by the previously mentioned vertex group. No texture is required (although you can optionally add one), just adjust strength and displacement distance values as necessary.



You can move your worm mesh around and it will deform according to both position and shape.