fitness band case 3d model

Create a Samsung Galaxy Fit3 snap-fit cover for FDM 3D printing. Front completely closed and opaque black to hide the screen. Back has a rectangular sensor opening 18 mm × 12 mm centered for heart-rate sensors. Internal cavity 43.5 mm × 29.2 mm × 10.2 mm. Wall thickness 2 mm. Right-side button cutout 14 mm × 8 mm. Two internal snap clips on top and bottom. Watertight STL. Functional mechanical part, not decorative. Engineering CAD style.