This article describes a novel method for fabricating three-dimensional (3D) microfluidic devices using stacked layers of patterned paper and double-sided adhesive tape. The 3D μPADs (microfluidic paper analytical devices) are designed to distribute fluids vertically and laterally, enabling complex microfluidic paths and the distribution of microliter volumes into arrays of detection zones. These devices are lightweight, low-cost, and do not require external pumps, making them suitable for resource-limited settings such as developing countries, environmental monitoring, and water analysis. The fabrication process involves patterning the paper with hydrophilic channels and hydrophobic walls, and the tape with holes to connect channels between layers. The devices can be used for simultaneous detection of multiple analytes, generating calibration curves, and performing colorimetric assays. The simplicity and cost-effectiveness of these 3D μPADs make them promising for a wide range of applications, including diagnostics, drug development, and environmental monitoring.This article describes a novel method for fabricating three-dimensional (3D) microfluidic devices using stacked layers of patterned paper and double-sided adhesive tape. The 3D μPADs (microfluidic paper analytical devices) are designed to distribute fluids vertically and laterally, enabling complex microfluidic paths and the distribution of microliter volumes into arrays of detection zones. These devices are lightweight, low-cost, and do not require external pumps, making them suitable for resource-limited settings such as developing countries, environmental monitoring, and water analysis. The fabrication process involves patterning the paper with hydrophilic channels and hydrophobic walls, and the tape with holes to connect channels between layers. The devices can be used for simultaneous detection of multiple analytes, generating calibration curves, and performing colorimetric assays. The simplicity and cost-effectiveness of these 3D μPADs make them promising for a wide range of applications, including diagnostics, drug development, and environmental monitoring.