Kupros Cu29 Is a Conductive Copper Filament That Prints Circuits on Desktop Printers

The Filament That Proved a Skeptic Wrong

Ian Ramsdell started Kupros after an electronics expert told him copper could never be 3D printed. That expert was wrong. Ramsdell already had a validated Navy lab experiment in his corner, one that proved copper conductors could work on fused deposition modeling hardware. Cu29 is the result.

The filament is not solid copper. It is a fully metallic, conductive composite that prints on standard FDM machines with a steel hotend. No special sintering, plating, or chemical cleanup is required. The printed conductor works straight off the bed.

What It Is Actually For

Cu29 is not meant to print bulk copper parts. Ramsdell says the team has tested layer heights of five or six in the Z axis, mainly to check self-adhesion. The real goal is embedded electronics: conductive traces laid into and onto plastic structures during the same build. A dual-extruder or IDEX printer can lay down structural plastic and copper path in one job.

The use cases are specific. Conformal antennas that follow a part's geometry. Integrated sensors inside load-bearing structures. Signal routing that replaces flat circuit boards. In aerospace and defense, fewer wiring harnesses and connectors means less weight and fewer failure points.

Who Is Buying It

NASA, Northrop Grumman, and Boeing placed pre-orders before the material was finished. So did KBR, the US Army DEVCOM, and several universities. Buyers put money down while the science was still in development. That kind of pre-revenue confidence is rare.

The underlying technology came from a US Navy lab. Scientist Carson Holmes developed the concept while working on additive electronics systems. Ramsdell licensed it in 2021 through a Department of Defense startup studio. One large electronics manufacturer told Ramsdell it had been trying to make similar material since the 1990s without success.

The Performance Numbers

Kupros claims Cu29 handled 12,500 volts in early high-voltage testing without breaking down. The team kept raising current until power supplies failed. A supercapacitor bank pushed over 600 amps through a short sample, still without destructive failure. Against silver inkjet, the only comparable additive electronics process, Kupros claims Cu29 is 48,000 percent more conductive. Those figures are company-stated and await independent verification.

A space-grade variant called Cu29 Space is in development. It targets tin whiskering, a failure mode where tin conductors grow tiny filaments that can bridge adjacent traces and short a circuit. The Space variant is designed to eliminate whiskering while printing traces from 0.2 mm to 1.2 mm on typical FDM hardware.

What It Means for Makers

Cu29 works on sub-$300 desktop printers. Ramsdell has tested it on a Bambu Lab A1 Mini and is qualifying the Prusa XL. Only a steel hotend is required. The material opens functional electronics to anyone with a dual-extrusion setup and an idea. Whether that means a custom keyboard backlight, a sensor-laden drone part, or a one-off prototype, the barrier to entry just dropped from six figures to a spool of filament.