Smartwatches are becoming so varied it's hard to know what to buy. Even then it's unclear if you'll need to splash for a new one a few months later. Enter Blocks, the modular smartwatch that you can upgrade as and when you need.

Much like Google's Project Ara smartphone, expected out in January, Blocks uses sections which can be added to upgrade the smartwatch. The idea is that everyone wants different things so each person can buy the watch suited to them, rather than wasting money on sensors they don't need.

Blocks also means upgrading doesn't involve the huge expense of shelling out for a new device every time something new is announced.

Each parts of the Blocks modular smartwatch can be changed. This includes display, camera, GPS, motion sensor, fingerprint reader, HR sensor, microphone, audio jack, SIM card, O2 sensor, temperature gauge, gesture controls and likely more.

Say you want to add GPS for tracking runs or walks, you might want to save battery elsewhere by using an E Ink display rather than a full colour LCD. Or perhaps you want a camera and decent screen with SIM so you can snap, check and share photos.

Blocks is also open source so the apps that develop can be created by anyone – a third party developer of a hardware sensor, for example. Each bit of hardware attaches as another link in the wrist worn chain. Dummy blocks can be used to fill in the rest of the space.

While Blocks is still in the developmental stages it's a great idea. Although we wonder how users that want everything will fit them all on a wrist. Or will they only be for those with giant wrists?

There's no launch date mentioned by Blocks just yet but we'd hope it'll arrive to back up Project Ara around January 2015.

READ: Google’s modular Project Ara phone to arrive by January 2015