Miniaturization of cameras and LiDAR sensors has enabled the development of wearable 3D mapping systems for emergency responders. These systems have the potential to revolutionize response capabilities by providing real-time, high-fidelity maps of dynamic and hazardous environments. We present our recent efforts towards the development of such ultra-portable 3D mapping systems. We review four different sensor configurations, either helmet-mounted or body-worn, with two different mapping algorithms that were implemented and evaluated during field trials. The paper discusses the experimental results with the aim to stimulate further discussion within the portable 3D mapping research community.