Kupros Cu29 Filament Lets You Print Copper Circuits on a Desktop 3D Printer

The Skepticism Was Immediate

When Ian Ramsdell started telling people he was trying to 3D print solid copper, he hit a wall. An electronics specialist told him it could not be done and never would be. The skepticism was understandable. Copper reflects laser energy, conducts heat away from the melt zone faster than almost any other metal, and forms an oxide layer the moment it crosses a few hundred degrees Celsius. Those properties have kept copper out of reach for virtually every consumer-grade additive process.

The Source Was Not Guesswork

Ramsdell was not starting from scratch. The underlying chemistry came out of a US Navy lab, developed by scientist Carson Holmes while working on additive electronics systems. The Office of Naval Research named it the top paper of 2017 under its Design Innovation Award. Ramsdell licensed the technology in 2021 through a Department of Defense startup studio, then spent years translating a lab-proven concept into something that could run on a sub-$300 printer.

The result is Cu29, a fully metallic conductive filament now shipping to early customers. The name is Greek for copper, a deliberate nod to the civilization that first worked the metal into tools.

NASA, Northrop, and Boeing Ordered Before It Shipped

Kupros did not run a crowdfunding campaign. It collected pre-orders. Ramsdell walked out of the 2022 DMC conference in Tampa as an Army xTech finalist with prepaid commitments from NASA, Northrop, and Boeing. The US Army DEVCOM, KBR, and several universities followed. Buyers put money down while the material science was still being finalized.

The pitch was specific: no more silver inkjet printers costing six or seven figures, no sintering step, no curing, no chemical cleanup. Print Cu29 on a standard FDM machine with a steel hotend, and the conductor is functional straight off the bed.

What the Numbers Actually Say

Kupros claims early high-voltage testing pushed 12,500 volts through the material without failure. The team kept raising current until they were blowing power supplies. A supercapacitor bank later drove what Ramsdell estimates at more than 600 amps through a short sample, still without destroying the trace. Against silver inkjet, the only real comparable additive conductor, Kupros claims Cu29 is 48,000 percent more conductive. Those numbers are company-stated and await independent verification, but the TCT Materials Award at RAPID + TCT 2026 suggests the industry is taking them seriously.

How It Actually Prints

Cu29 is not for printing bulk copper parts. Ramsdell says the team has tested only five or six layer heights in the Z axis, mainly to check self-adhesion. The real use case is embedded electronics: structural plastic and conductive copper printed together on a dual-extruder or IDEX machine, so signal routing, sensors, or antennas are built into the part rather than mounted on a separate board.

Kupros has tested Cu29 on the Bambu Lab A1 Mini with its automated material system and is qualifying the Prusa XL as a recommended platform. A Space variant is also in development, formulated to suppress tin whiskering for traces between 0.2 mm and 1.2 mm on standard hardware. That matters for spacecraft, where a single shorted trace can end a mission.

What This Means Right Now

Embedded electronics has required specialized, expensive equipment since the field existed. Cu29 is a direct challenge to that assumption, if its performance claims hold up under independent testing. For defense contractors already building parts with structural and electrical requirements together, a copper filament that runs on a machine you already own is a meaningful shift. The broader maker community will also pay attention, even if the aerospace and defense use cases are driving the early business.