While driving towards the American Precision Museum, a place where interchangeable parts were developed, I had an interesting realization.

The original desire for creating interchangeable parts was to facilitate mass production of identical rifles. Rifles could be assembled from a set of parts which were previously unknown to each other and then put together, in random permutation, to achieve many functional - identical - rifles.

But when we say “interchangeable”, the components really need not be identical.

A grip can mount to a lower with the same bolt and pin pattern - but have a different size, texture, color, or other features that do not affect the interface. What matters is that the interface is identical (or at least compatible). With the interface clearly defined, an enthusiast or aftermarket parts manufacturer can produce new upgrades.

This works best if the interface is simple and easy to understand.

This is precisely the reason that sometimes, manufacturers produce difficult and complex interfaces: to inhibit the production of interchangeable alternatives. This decreases redundancy and instead increases frustration. What motivates a manufacturer to do such a (horrid) thing?

The most revolting reason is of course, money - a manufacturer can more easily lock their customers into their ecosystem and so command a higher premium. Better (but still, I argue, inexcusable) reasons would be safety - the manufacturer doesn’t want inferior grade products being used which could cause damage. More often the latter is an excuse for the former.

Is the safety worth the frustration? I argue not - I’d argue that technologies are most unsafe when they are frustrating; when they increase the level of cognitive energy required to use them to a point of overwhelming; to a point where their users break the technology in order to accomplish the thing they wanted: to put a new, repaired, or better part on; to extend functionality or restore function.

Interfaces of technologies should not box in what can be attached to them more than is necessary - allow interchanging of components, not identicality.