tt, in another thread; you or another member were wishing for a way to kick-start development for boards that require 4 layers in order to make all the connections.

Suggestion:

Almost every single sided PCB that I've seen in PSU and KBD matrix applications, wires on the component side jump across across traces on the copper side, effectively implementing a two sided layout on a single sided board.

Doing a two sided "Seed board," with vias designed in for patch wiring these same impossible connections would effectively convert a two sided proto-board to four sided function, sans the additional ground fill planes, of course.