The minds behind the Blocks modular smartwatch just launched a Kickstarter campaign with the hopes of raising $250,000 to build its watch. Modular smartphones haven't really taken off yet, despite a few valiant efforts, but the London-based group of technologists is hoping that the smartwatch will prove to be a better candidate for put-it-together-like-Lego technology.

Backers who spend $195 will receive the "core" of the Blocks smartwatch and a strap, while those who pledge $275 will get those items plus four modules to snap into the smartwatch. Blocks Wearables says the Blocks watch is expected to ship by next May.

The Blocks watch, in case you missed the initial press push around CES, is at its core a basic, open-source smartwatch. It pairs wirelessly with both iOS and Android devices to show notifications. It has a color touchscreen, an accelerometer and gyroscope, and a microphone for voice control. Blocks Wearables estimates the battery life to be about a day and a half. Interestingly, Blocks was a finalist at Intel's Make It Wearable challenge last year, but the Blocks Wearables team ended up partnering with Qualcomm for this Kickstarter-ready product, building it with a Snapdragon 400 processor.

The additional snap-on modules are what makes the smartwatch stand out. You can add an extra battery module for up to 20 percent more battery life, a heart rate sensor, GPS, and an "adventure" module that adds temperature, altitude, and air pressure sensors to the watch. And the Kickstarter page suggests there's even more to come — a fingerprint module, a SIM card option, and a camera module, for example.

Whether or not the Blocks watch and all of its modules interoperate well remains to be seen, as does impact on battery life — which is one of the challenges of modular devices that Google acknowledged during the development of Project Ara. Startup Pebble has also said it would partner with outside hardware makers to create "smartstraps" that would add capabilities like GPS or extra battery life to newer Pebble watches, but so far we haven't seen many that are actually available to consumers.

Blocks Wearables says it has partnered with "major tech companies" to develop more modules, and that a software development kit for the Blocks watch will be available soon.