The MS3's housings are fashioned from 5-axis CNC aviation-grade aluminum alloy with surface anodization. The shells are built like a tank and will probably survive a drop (don't try this at home!). There's a flame-like motif on the faceplate, which is quite unique compared to the usual silverish or matte black competitors.
Weighing in at 15 g apiece, the earpieces are light. Ergonomics are also top-notch, with no weird protrusions on the internal aspects to poke the ears, and the earpieces are very smooth to the touch.
The air pressure equilibrilization on this IEM seems to have been thoughtfully designed, with no driver flex noted. Despite being vented, isolation is average and the MS3 is quite usable for outdoor activities.