2009

Attachment constraints keep the cylinders on the surface.
The Attachment constraint is a position constraint that attaches an object's
position to a face on another object (the target object doesn't have to be a
mesh, but must be convertible to a mesh).
By keying different attachments over time, you can animate the position of
an object over the irregular surface of another object, even if that surface is
changing over time.
Procedures
Example: To attach a cone to a bending cylinder:
1 In the Perspective viewport, create a cylinder with a radius of 20, a height
of 30, and 10 height segments.
Attachment Constraint | 3289