"Programmable Filament" Allows Any FFF 3D Printer to Print Multi-Material Objects

Researchers at Meiji University, Osaka University, and Texas A&M University have detailed "programmable filament," designed to let unmodified fused filament fabrication (FFF) 3D printer print multiple materials in a single model.

"From full-color objects to functional capacitive artifacts, 3D printing multi-materials became essential to broaden the application areas of digital fabrication," the researchers write in the paper's abstract, brought to our attention by IEEE Spectrum. "We present Programmable Filament, a novel technique that enables multi-material printing using a commodity FDM 3D printer, requiring no hardware upgrades."

"Our technique builds upon an existing printing technique in which multiple filament segments are printed and spliced into a single threaded filament. We propose an end-to-end pipeline for 3D printing an object in multi-materials, with an introduction of the design systems for end-users. Optimized for low-cost, single-nozzle FDM 3D printers, the system is built upon our computational analysis and experiments to enhance its validity over various printers and materials to design and produce a programmable filament."

Producing a part using the programmable filament is a two-stage process. First, a computer model works out which parts of a roll of filament should be what particular material and then a spiral of filament is printed on an unmodified printer. For each new material, the printer pauses and allows itself to be fed with a new reel of single-type filament until the multi-material printed filament is complete. This filament is then fed through the same printer to produce a single-print model using all the materials required.

The team tested the approach using four different off-the-shelf and unmodified printers: A Creality CR-10S, Prusa MK running the Teacup firmware, Creality Ender 3, and NWA3D, with success — though did highlight that the approach adds an upper limit to the length of filament which can be created, which can be bypassed by printing multiple lengths of filament over multiple stages.

The team's paper is available under open-access terms (PDF warning).