Blocks, the wearable smartwatch you configure yourself out of expandable modules, is going live on Kickstarter tomorrow—and that should tell us something about the market’s appetite for a device that offers customization as its main selling point.

The Blocks device is built around a core watchface unit with a cut-down version of Android Lollipop on board. Bluetooth, Wi-Fi, motion sensors and a microphone are included, as well as a Qualcomm processor. This enables the watch to show smart notifications and track activity.

After that, it’s up to the user what else gets added—the extra modules make up the strap. The modules available at launch will be an extra battery block, a heart-rate sensor block, a location (GPS) block, and a contactless payments (NFC) block. More modules are apparently on the way, both from the Blocks team itself and “private companies, researchers and a community of developers” involved with the project, the company says.

And those developers could be key. Hardware and software makers are going to want to see strong user demand before they devote resources towards the Blocks watch. In turn, users are only likely to be tempted in if they see some compelling modules available. A SIM card module is one of the components on the way, according to the London-based Blocks team.

It’s a strategy similar to Pebble’s smartstrap push, using the watch band as a way of adding extra functionality, whether that’s from Pebble itself or a separate company with an interesting idea.

Pebble CEO Eric Migicovsky has admitted it’s going to be next year before the first smartstraps go on sale. Deus Ex Aria, which adds Bluetooth gesture control, was successfully funded on Kickstarter back in July but isn’t expected to see the light of day until May 2016.

Building With Blocks

Cutaway of an existing Blocks module.

Blocks isn’t expecting to get developers on board building modules until after the Kickstarter campaign has concluded, but there’s already a sign-up page where interested parties can register for updates.

“The core of the smartwatch will run a modified version of Android Lollipop, enabling you to leverage your existing tools to build apps for Blocks,” explains Blocks on that page. “We are also working on an Android API to allow you to manage and communicate with individual modules.”

Do Add-Ons Add Up?

Aside from the once-flourishing market in expansion cards for desktop PCs, there have been few success stories in creating markets for hardware add-ons. In the personal-device market, there was the Handspring Visor, an expandable version of the old Palm personal digital assistants. Palm ended up buying Handspring and abandoning its “Springboard” expansion slot as it went into the smartphone business.

But the wearable market may well be different; it is far cheaper and easier to create hardware nowadays, especially if you’re not responsible for coming up with the whole widget.

Block’s open platform approach means that individual startups and developers can explore new ideas for wearables without having to build a new smartwatch from scratch—creating wearable strap modules is a much less daunting proposition.

And Blocks says that should mean niche requirements can be catered for as well. Features that just aren’t popular enough to get into something like the Apple Watch could come to life as strap components that serve a small group of loyal followers.

A modular approach means upgrades are required less often: Users can get the latest GPS or NFC technology by swapping out a link in their smartwatch bands. That in turn means less gadgetry heading to the world’s overcrowded landfill sites.

Outside of the consumer market, companies and organizations could build customized Blocks watches for their staff that have specific goals: advanced health sensors for doctors working remotely, for example, or tracking tags for construction workers on a busy building site.

Smartwatch sales have been steady rather than spectacular so far, but perhaps the wearable holdouts are waiting for a device they can truly personalize and call their own. When the Blocks Kickstarter launches at 9 am Pacific Time tomorrow, we’ll find out.

Images courtesy of Blocks