[dvgrn]

Von Neumann's 29 states were custom designed to make it easy to construct passive configurations, similar to the way a 3D printer builds things -- one layer at a time.

You can't do that in Conway's Life, because stable patterns in Life aren't necessarily stable when you add one cell at a time. But you can do the next best thing, which is to design circuitry that's made out of small stable "Spartan" pieces -- and then build the pieces one at a time.

Related to this, there's an equivalent for building passive structures and then activating them. In Life you can build a static "one-glider seed constellation". Hit the stable constellation with a single glider, and a few ticks later you have a working spaceship. Example:

http://www.conwaylife.com/forums/viewtopic.php?f=&p=57674#p5...

However, there's no reasonable expectation of figuring out how to build a one-glider seed for the Sir Robin knightship any time soon -- the knightship is way too fast, active, and complex. With current techniques a search for such a thing would likely take millions of years.