We present Candyfluidics, a rapid and low-cost method for fabricating micro- and nanofluidic devices using sugar mixtures patterned by screen-printing. The process (from screen preparation to PDMS casting) takes less than 30 minutes, supports parallel production of multiple chips, and exploits household materials and simple technology widely available in low-resource regions. As a proof of concept, we fabricated flow-focusing chips and validated them by generating pressure-driven water-in-oil droplets with volumes from 0.2 to 1.22 nL. We further demonstrated the utility of the fabricated chips by performing digital droplet loop-mediated isothermal amplification to detect dengue virus type 1 nucleic acids at femtomolar concentrations (85 copies per μL). By lowering the cost and technical barriers to device prototyping, Candyfluidics offers an accessible approach to microfluidic manufacturing with potential for point-of-need applications for global health interventions.