Introduction
The shift from a linear to a circular economy is essential for reducing global resource consumption, minimizing waste, and promoting sustainable materials. This transition supports the development of bio-based thermoset polymers, the upcycling of industrial waste-derived fillers, and the use of environmentally friendly manufacturing technologies. Vat photopolymerization (VPP) has emerged as a highly versatile method with great potential. As a light-driven process, it enables high-resolution printing and the fabrication of complex geometries.

Materials and Methods
The resin formulation consisted of acrylate epoxidized soybean oil (AESO) and isobornyl methacrylate (IBOMA) in a 1:1 weight ratio, with 2 wt.% of phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide (BAPO) as a radical photoinitiator. Bamboo filler was added at 3, 5, and 10 phr to produce bio-based composites. Both neat and filled formulations were processed using a Phrozen Sonic Mini 8K LCD printer equipped with a 50 W linear projection LED module operating at a UV wavelength of 405 nm.

Results and Discussion
The addition of bamboo enhanced the mechanical and viscoelastic properties. The Young’s modulus increased from 1189 MPa (A-IB) to 1397 MPa (A-IB+B10), corresponding to an enhancement of approximately 17%. The storage modulus (E’) improved from 1140 MPa to 3324 MPa. The glass transition temperature shifted from 92°C to 95°C. Thermogravimetric analysis confirmed that thermal stability was not negatively affected. Although bamboo increased viscosity, it remained within the optimal range for VPP, ensuring processability.

Conclusions
This study demonstrates that bio-based photocurable formulations can be efficiently used in VPP to produce high-performance composites. Bamboo filler provides sustainable reinforcement, improving mechanical and viscoelastic performance without compromising printability or thermal stability. These findings highlight the potential of combining bio-based resins with natural fillers to develop sustainable, high-performance materials for AM applications, contributing to the broader goals of the circular economy and green manufacturing.