This is a demo object for a universal connection priciple.

Holding together multiple parts (reversibly) usually requires screws springs or magnets.
But there is yet another method! By using the next connection pin to prevent the former from sliding out one can e.g. use just only one magnet at the last connection pin to hold a whole structure together. This is a special case of a great class of structures.

If one pin locks multiple pins one gains a branching tree structure (topologically).
It should be possible to extend this principle to two or three dimenstions. CALLENGE!
With usage of branching the hole circumference or surface enclosing an area or volume filled with lots of elements could be locked at one single point.

In an other context:

Block based "Modular Molecular Composite Nanosystems"
out of stuctural DNA nanortechnology (DNA Bricks & co) as presented here
http://metamodern.com/2008/11/10/modular-molecular-composite-nanosystems/
may help us gaining robotic (more generally stereotactic) control at the nanocosmos.

In that respect an interesting question is:
Would it be possible to construct a linkage / placement mechanism composed out of a few hundred standard blocks of a vew dozen types that can assamble a great range of structures out of those same blocks including a copies of itself?

Creating and handling standard blocks may be easier than having a multitude of objects that each require special treatment in synthetisation and assembly (or may not).

A hirachical locking structure of molecular blocks in machine phase (~= stuck to a place not brownian tumbling) makes accidental breaking of connections (that otherwise would only be held together by VdW force) more unlikely.

The downside: building rods this way introduces compliance or even backlash that adds up proportional to the number of stacked elements.

In advanced atomically precise products this connection principle in its generalized form will undoubtably play an important role.

Tipp: For disassembly of the assembled stack the small blade of a swiss army knive is useful.