A multi-gas personal monitor warns users of hazardous gas present in their working environment. It has the capability to monitor up to five gases at a time with its four gas sensors, one being a dual sensor. We had the opportunity to mechanically, electrically, and aesthetically design the entire product family–the hand-held monitor, single charger, add-on pump, and gang calibrator-charger.The products are intrinsically safe, including an intrinsically safe battery pack. Through sealed geometry and material selection, we designed the products to meet IP65 ratings (e.g. water and dust tight) and also UL (Underwriters Lab) classification. We provided the necessary communications between UL and in-house testing of the product to complete such standards. Mechanically, the hand-held device has custom-designed sealed ports, as well as a sealed auditory system. Detailed Solidworks modeling helped create efficient moldable parts, including some over-molded components, and integrated buttons push through the case to activate the PCB. In addition, the light pipe design for the LEDs used to indicate the charging status on the single charger avoids light bleed; thus, displaying a clear, bright light that is easily seen from a distance. Within the gang calibrator-charger, avoidance of gas leaks and cost optimization were achieved by combining components into a single moldable part. Electrically, we used schematic drawings detailing part selections and electronic connections to consider required components for intrinsic safety and other ratings. Closely working with mechanical engineers, board layouts for the numerous boards within the product family were meticulously designed to carefully consider physical dimensions and constraints, mechanical layout, and appropriate spacing. Printing 3D components allowed for an easy and quick assessment of design feasibility. One of the biggest challenges with this project was creating a high-contrast, high-resolution, wide temperature range display that met intrinsically safe requirements. We accomplished this feat by designing a custom display. Another successful accomplishment was within the gang calibrator-charger; we re-designed the manifold to significantly reduce the number of tubes used from 30 to eight.