Prusa Research has introduced an actively foaming filament called Prusament PLA Lightweight. Announced on 17 September 2026, it can produce parts up to 65% lighter than conventional PLA, according to the manufacturer, while the same spool mass may yield two to three times the model volume. It targets RC aircraft, drones, cosplay, floating models and other objects where mass matters more than maximum strength.

Temperature also controls density

The filament begins to foam more strongly above roughly 215°C and, Prusa says, reaches maximum expansion around 235°C. Gas bubbles allow the same feed mass to fill a larger cross-section, so flow must be reduced substantially. The factory profile uses 230°C and a 0.45 extrusion multiplier, but a different temperature requires renewed calibration.

Greater expansion is not free. It creates paler colour, a rough matte texture similar to an SLS surface and lower material density. Lower mass generally also reduces the strength and stiffness available from solid polymer. Designers should therefore seek the lowest safe density for the function rather than maximising a weight-reduction percentage.

Why profiling is difficult

Active foaming is sensitive to temperature, flow and residence time in the nozzle. Oozing, stringing and seam irregularity may be more common than with standard PLA. Prusa recommends routing travel inside walls, limiting detours to 40 mm and printing objects sequentially where appropriate. The manufacturer advises against temperatures above 250°C because of degradation and fumes.

Calibration can use a simple single-wall specimen with known volume. Print the same geometry at several temperatures and multipliers, then compare mass, wall thickness, surface and a bending or break test relevant to use. Fan, speed and layer time must remain controlled or the responsible variable cannot be identified.

Moisture and machine support

Foaming PLA is hygroscopic. Prusa specifies five hours at 55°C for drying after moisture exposure. External water vapour combined with the intended internal foaming reaction can create unstable extrusion, popping and poor surfaces, so dry storage is a functional requirement rather than cosmetic housekeeping.

At launch, published profiles covered CORE One+, CORE One+ gen2, CORE One L+ and MK4S machines. The material may work elsewhere, but the user must validate temperature, flow and retraction. Prusa announced five colours and launch prices of $56.99 or €59.90 including VAT.

Verified fact, manufacturer claim and conclusion

Verified facts are the product, published baseline profile, supported machines and drying guidance. Up to 65% weight reduction and two-to-three-times model volume are manufacturer claims dependent on temperature, geometry and chosen density. LAYERTIMES concludes that PLA Lightweight is not merely a low-density PLA but a thermally tuned foam system; useful results require mechanical performance to be measured alongside mass.