A Hollow-Tube Approach Could Make Large 3D Prints Much Faster

A small experimental project from Roetz 4.0 suggests that the future of large-scale 3D printing might look more like blow molding than fused filament fabrication. The team built a printer that extrudes hollow plastic tubes inflated from the inside with compressed air, creating structures that are mostly empty space but rigid enough to hold shape.

The core problem with big FDM prints is simple: size quadruples the amount of material and print time. Widening the nozzle helps, but you end up with coarse surfaces and very heavy parts. Roetz 4.0's concept sidesteps both issues by printing air-filled cylinders with thin walls. Depending on the tube diameter to wall thickness ratio, the final part can be up to 90 percent air. That drops material cost and weight dramatically while letting the machine lay down thick layers quickly.

The hardware is not trivial. The nozzle has a central air channel, and the system must balance temperature, pressure, and extrusion speed in real time. After extensive tuning, Roetz 4.0 still could not reliably print a simple single-wall cylinder. The concept is promising, but it is not ready for production.

Where it could land first is in construction and large industrial parts where surface finish matters less than structural strength per unit of material. Boat hulls, exterior cladding, and equipment housings all fit that profile. If the engineering team resolves the stability issues, hollow-tube extrusion could become the fastest way to build big, lightweight objects without switching to a completely different manufacturing process.