Smartphones are the epitome of planned obsolescence. If you don’t upgrade your phone every two years, you’re likely to be left out in the cold as software outpaces its capabilities. But all you really need to do is upgrade the phone’s brain, not its whole body. What if there were a smartphone whose body was designed to let this kind of modular upgrading happen? Julius Tarng has created one called Modai . It’s only a concept design, not a working prototype or a shipping product, but I wish it were.

Tarng has devised a boatload of intriguing user-interface conventions for Modai, some familiar (separate “paradigms” for work and play, much like Divide), some more surprising (a flexible “peelstand” on the back of the phone lets it flex in your pocket to silently signal incoming messages, or stand up on edge when an alarm goes off).

But Modai’s coolest idea is its modular design to encourage users to extend the device’s lifespan. Removing the “peelstand” also lets you access Modai’s “internal pack,” which you can swap out and attach a new, better CPU unit, RAM cache, or battery to, just like snapping Legos together. “From batteries to the camera, from the RAM to the CPU, most internals that evolve quickly can be upgraded,” Tarng writes. “Modai employs an ecosystem that allows you to return your old module for disposal or resale after you buy a new one.”

In the same way that talk is cheap, so are concept designs. Modai is an awesome idea, but fabricating and manufacturing all its components, as well as spinning up the infrastructure to support the trade-in/recycling “ecosystem,” would be a mammoth undertaking, and perhaps not practical. Then again, “perhaps” is the operative word there. Modai looks like something that should exist. We’ll never know if it could exist until someone actually tries.

[Read more about Modai]