One way to be certain to raise our dander here at oomlout is to make it unnecessarily difficult to repair, tinker with or outright replace parts of a project. This is naturally true of commercial, off-the-shelf devices from large companies - who use anti-consumer techniques ranging from bizarre security screws through to gluing everything into place - but is something of which makers can be guilty, too. The path from prototype to product, even through extremely small-scale manufacturing in the home, is full of little non-obvious steps that can be missed - as Dan Royer of Marginally Clever has noted. Dan has, to our great delight, taken up the call of Sarah Petkus at RobotArmy and begun ensuring that all laser-cut components in his robotics kits include etched and wholly unique part identifiers. It's a simple step, but one which transforms the experience: a broken part can now be quickly and cheaply replaced by simply looking up that individual component on his site, rather than having to order an entire bundle of parts or attempting to describe via email which of several near-identical components has actually broken. It also makes assembly easier by addressing each part by name, resulting in quicker builds with fewer frustrations. In short, it's near-vital and yet something that would be all to easy to overlook when beginning production of your own designs.
Now that I have separate part numbers I can: file that one extra piece sometimes left over after a production run and give it a kanban card; refer to them by name in the assembly documents and tutorials; sell them individually as replacements; and discuss them in the forums with people.