So, I've been playing this game for, what, nearly 20 years now? And I just happened across the page about Blueprints on the Creatures Wiki.
"Blueprints are agents first introduced in Creatures 3 and Docking Station used to hold information on how to connect Gadgets to make Machines.... If a blueprint is put in the Creatures 3 Replicator, then it will replicate the necessary gadgets needed for making the machine."
Wait, what? Let's go to the Replicator page; maybe there's more information there.
"Another feature of the replicator is its ability to create all the required parts of your newly-designed gadgets by replicating their blueprint. To do this, create your gadget by wiring its appropriate nodes together, use the context help to open a window about any one of your nodes, and press the button next to the red one in the top right. This should create a blue rectangular object."
I had absolutely no idea you could do this. How did I miss this? All these years, I've been manually replicating stuff! It can't really be that easy, right? I opened up the test world and chucked some random gadgets together for a quick test, and sure enough, on opening the tooltip for one of the component gadgets, there was the button that I had - somehow - never noticed before. A little arrow going through a circle, right next to the red "close" button. Clicked it; out popped a blueprint.Well, I'll be. Sure enough, when I put it in the replicator, it spat out a radio, a not gate, and a light. How did I not know about this?