Experimental circuit boards can be easily made with a 3D printer. They can be made at the same size and thickness as a standard 1/16" thick, through-hole soldered, perfboard.
The components can be fairly easily connected together without using solder.
This technique is somewhat faster than standard etched and soldered circuit boards. But it does require some skill and attention to detail to create a reliable circuit.
This example circuit board is a simple micro controller circuit that flashes three LED's in sequence.
It is intended to be a minimal illustration of what is possible.
The short video below shows the circuit working.http://youtu.be/vQuPP3--fxk