By day, Emile Petrone was a web programmer. But in his spare time, he would tinker with the Arduino and the Raspberry Pi, two inexpensive kits that let you build your own hardware devices.

This was 2012, when other creative types were beginning to build "indie hardware" in similar ways. As he browsed online hangouts like Hacker News and Reddit, Petrone kept stumbling onto discussions of these hardware hacks, which provided inspiration for his own projects. The trouble was, he had no way to get his hands on them.

So, in his own post to Reddit, Petrone proposed an online marketplace for indie hardware, and two and a half months later, he launched the thing. The site is called Tindie, and it's now a thriving operation. Over the past two years, Tindie has listed more than 2,000 products, with 200 of those arriving online in the last month alone, and it has processed more than 10,000 orders. Sales have doubled since February. And powerhouse venture capital firm Andreessen Horowitz is among those that pumped $1.2 million into the startup during a seed funding round.

The tech cognescenti love talking about Kickstarter as a place for bootstrapping hardware projects. But the less-glamorous Tindie could prove just as important to the evolution of hardware design. Where Kickstarter is all about funding slick and shiny products that haven't been built yet, Tindie is a straightforward marketplace for cruder devices that already exist, devices often built in small batches with limited amounts of capital. The result is a community of indie hardware makers who can feed off each other, a place that can help bootstrap a much wider revolution in hardware design.

>The result is a community of indie hardware makers who can feed off each other, a place that can help bootstrap a much wider revolution in hardware design.

The site is a bit like the indie marketplace Etsy, except it's focused on hardware devices instead of jewelry, clothes, and other traditional craft items. And it's built to last. Tindie charges hardware makers a 5 percent commission to list on its website, plus another 2 to 3 percent for payment processing.

Tindie is not yet profitable, but the company seems to have caught an amateur hardware hacking wave that's only just beginning to take off, a wave that could decentralize the creation of hardware in much the same way that the boom in open source change how we build software. "We see a big trend emerging in empowering designers to do small batch manufacturing as desktop tools for designers are getting more sophisticated," says Cyril Ebersweiler, founder of HAXLR8R, a startup accelerator and venture fund that focuses on hardware. "Tindie could be at the forefront of that more advanced marketplace."

The number of people using platforms like the Arduino and Raspberry Pi – single-board computers that serve as building blocks for larger devices – has multiplied in each of the past several years, as software for operating them has matured. And at Tindie, these people can share their designs with each other, creating a kind of feedback loop where one design can help inspire another. The initial buyers on the site were the same sort of DIY enthusiasts who were listing products. But this group has diversified to include educators, music lovers, and employees at large companies and government agencies, including NASA, Google, Intel, and Nokia.

To Petrone, this grassroots movement looks a lot like the early days of personal computers, when hobbyists would gather to show off their crude, homemade inventions – bare circuit boards with wires and diodes pointing this way and that. "A lot of the projects we have on Tindie today look exactly like that," Petrone says.

Petrone ran a brief experiment with crowdfunding on Tindie, but now positions the site as a sort of anti-Kickstarter. It's notoriously hard to predict costs and set prices correctly on Kickstarter because none of the items up for sale have not been fully developed. On Tindie, you can only sell what you have in hand. "The types of companies we're trying to help are trying to grow the old fashioned way – by saying: 'Here's this idea. I've built ten or twenty or five,'" Petrone explains. "They get them out there, people buy them, and they go through that process again. If there's demand, they'll scale that up."

Top selling items on Tindie include various environmental sensors, like Chirp, which monitors moisture in plant soil. Tindie also boasts an awful lot of music hardware, such the ARPIE MIDI apreggiator, which converts musical chords into a rapid sequence of notes that can be played by a MIDI synthesizer. And then there are testing beds such as the Tapster, a robot that can simulate the way humans tap on a smartphone, letting developers run complex automated tests on their apps.

Right now, the number one product on the site is the AirPi Kit, a Raspberry Pi-based weather station developed by a 16-year-old and 17-year-old for a London science competition. The initial run sold out, reaping $30,000 to $40,000 in revenue this past fall, Petrone says, before the high schoolers learned how to manufacture them in larger quantities between classes. The project has worked out well for the teenagers. But it isn't just about them. Their success may inspire others.