In this paper, we propose a roll-to-plate (R2P) projection micro-stereolithography (PSL) 3D printer, where layers of photopolymer are transferred and photopolymerized through a flexible membrane. Benefitting from the "coat-expose-peel" procedure, highly viscous material can be printed quickly with good vertical resolution. Most importantly, the multinozzle dispensing method enables the fabrication of multimaterial architectures with high throughput, low material consumption, and low cross-contamination. R2P-PSL exhibits superior features for flexible 3D printing in terms of material complexity. For this purpose, we envision infinite scenarios involving potential applications in bionics, biotechnology, microcircuit graphics, photonic devices, microfluidics and material science.