Ever faced with the prospect of wanting to upgrade just one part of your smartphone? Maybe you’d like a better camera, but you’re happy with everything else? Or you could do with more storage space? A designer is now pitching a widespread concept called Phonebloks, which, while technologically unfeasible, would allow for a completely modular smartphone.

The concept comes from Dave Hakkens, who sees it as a way around the planned obsolescence and e-waste of modern smartphones. Rather than just chucking it out and replacing it every couple of years, you could install just the new bits you wanted on a universal back, all slotting into place like Lego.

It’s a noble concept, but one that ignores much of the reality of how tight the engineering constraints are of modern engineering. Look at a teardown of a smartphone, and how little free space there is — you wouldn’t be able to replicate that sort of size and performance using blocks like that. For a more detailed technical critique of everything wrong with this idea, both Reddit and Metafilter have it covered.

But that’s not to say that a modular concept can’t work at all. The Ricoh GXR had a modular lens/sensor combo that could slot into any body; and Bug Labs makes open hardware components that connect together for making custom devices. But getting all that into a smartphone sized package with the sort of performance that people expect is a long way off from what we can do now.