Indivisible protein like folding block chain
Base polyhedrons with simple geometry (e.g. cubes) that are inseparably connected on a long chain that can fold into complex shapes.
To qualify the base blocks must have a shape that greatly simplifies the self folding in comparison to proteins (even in comparison to the easier predictable de-novo proteins)
The blocks could be made from simple molecules like 3D-wiremesh DNA blocks (themselves self assembled in a more nontrivial internal geometry). A tool initially putting the blocks together has some superficial functional similarity to a ribosome but would be very different in the details. (TODO: this kind of thing needs a name)
Why a robotic version is highly dissimilar
On a bigger scale with technology further ahead such structures could be made as nanorobotic devices. In this case though the capability to couple together the base polyhedrons together or separate them at arbitrary points should not be too difficult to add. So there would be no reason to limit oneself to chain indivisibility. And if the base units are detachable from each other then its about single rotation joint reconfigurable shape robots instead.
- Illustration (Wikimedia commons): 
- MIT center for bits and atoms ...