Colton Baldridge's OS3M Mouse Is a Smart Open Source, 3D-Printable SpaceMouse Alternative

Electrical engineer Colton Baldridge, self-described "engineering dork," has put together an open source equivalent to the SpaceMouse 3D pointing device — offering six degrees of freedom (6DOF) for a fraction of the cost of off-the-shelf equivalents.

"I use a name-brand 3D mouse at work most days, but one day I came home and wanted the same capability here," Baldridge explains of the project's origins. "After discovering the cost of a normal 3D mouse ($150-400) and realizing that only one company had a monopoly on 6DOF mice, I set out to make my own. One that is 6DOF, mostly 3D printable, cheap, and open source."

The company in question is 3Dconnexion, creator of the famous SpaceMouse family of six-degrees-of-freedom pointing devices — handy gadgets to have when working with three-dimensional representations in computer aided design packages. Unable to justify the price tag for personal use, though, Baldridge set about building his own — and decided to make it open source, so that others could benefit from his efforts.

Baldridge started the project in mid-2022, designing the mechanics of the mouse and 3D-printing various custom flexures and knobs to experiment with their feel — a process that took longer than expected after he fell down the rabbit hole of finite element analysis (FEA).

An initial custom PCB design followed, with the first truly functional prototype and "minimum viable product" delivered nearly a year after the project began. Then, a five-month delay — "my life got busy," Baldridge explains — with another hardware revision required, resulting in a device which delivers on the maker's desire for something lower-cost, though higher-effort, than a 3Dconnexion device.

Baldridge isn't the first to build a do-it-yourself 3D-printed SpaceMouse equivalent. Back in March 2022 pseudonymous maker "FaultyDaantje" showed off a version built around a Pimoroni Tiny 2040, a compact development board based on the dual-core Raspberry Pi RP2040 microcontroller. The Space Mushroom, by maker "Shiura," is a more recent alternative — as is Salim Benbouziyane's unnamed but extremely sleek design. Jacek Fedoryńsk, meanwhile, took a different approach by building a Raspberry Pi Pico-powered adapter for old serial-based SpaceMouse Classic devices — available at a low cost on the second-hand market.

"Obviously the project is far from done," Baldridge says, outlining plans for future improvements. "The firmware is not great, doesn't support interrupts (though the hardware is there), is still using STM's HID [Human Interface Device] mouse example as the backend, and is not very easy to expand on for any expansion functionality you want to add."

"The software also is only a command line application which only supports SolidWorks," Baldridge continues, "whereas I have a dream of a GUI with configurable gains, many programs supported, and expansion button configuration. The hardware is also still not perfect, as I haven't updated the base to support the extra expansion header either."

For those who aren't put off by a work-in-progress, though, more details are available on the project's Hackaday.io page — while design files can be found on GitHub under an unspecified open source license, with the PCB currently in its third revision.