It’s an open source music player with an adorable name — Bumpy — and the shell is 3D printed on a Formlabs SLA 3D printer.

The approximate size of a business card, Bumpy is a compact digital music player that works just like an iPod Shuffle. But one key area of improvement is that the entire design is open source, from the firmware to the circuit board to the 3D printed case.

Another clever thing with Bumpy is how its simple appearance belies a sophisticated design. The casing as a ridged surface for a tactile feel (hence the name), whereas a combination of click-wheel and LED lights provides the user interface.

Fancy making one yourself? Of course you do. Creator Matt Keeter, an engineer at Formlabs, has shared the complete instructions to build a Bumpy on his workblog. He also explains his motivation on the official Formlabs blog:

“One of my goals for this project was to make something that looked like an actual consumer product. I didn’t want to finish the project with a bunch of bare circuit boards – I wanted to make a complete package, including the case.”

How does it work? Bumpy reads and plays MP3 files off a micro-SD card. Music is loaded onto the card and plugged in directly, or you can plug the device into your computer and it’ll show up like a flash drive.

The user interface is a click-wheel for changing volume, play and pause, and navigating forward and back through a playlist. Eight LEDs glow from beneath the case to show Bumpy’s status, with cute animations that provide feedback when changing songs.

In terms of power, the player houses a rechargeable battery which is recharged via a standard mini-USB plug. It should play for over 24 hours on a single charge.

The Hardware inside Bumpy is Anything But

The printed circuit board (PCB) inside Bumpy is smaller than a standard business card, and it’s powered by a 1000 mAh lithium ion battery.

Bought individually, the parts cost $58 to build a single board. But tantalisingly, if you wanted to build more than one player, the price drops to $35 in quantities over 100.

The firmware proved to be more challenging. While off the shelf software for playing MP3 files is easy to find, implementing a USB mass storage device required Keeter to program some new functions from scratch.

And the case? Well that’s the best part. While gainfully employed at Formlabs, Keeter used a Form 2 to print the shell at 50 micron layer resolution in white resin, using PreForm’s automatically generated support structures.

“The eponymous texture was actually an afterthought, ” he says. “I printed a few versions with flat tops and bottoms, but thought that it needed a little more character. It’s fairly subtle. The individual bumps are only 2 x 2 x 0.3 mm, but it came out great.”

It really did. And it has to be said, we have a tonne of respect for Formlabs for encouraging their employees to pursue their passions on company time.

To check out the documentation and source files, visit the Bumpy project page, look at the PCB and firmware repositories on GitHub, or download the STL files for the case exclusively from Pinshape.