Add Hat to 3D Scan and make it printable STL file

I already have a full-resolution 3D scan of my part; what I need now is a clean STL that includes a simple “hat” covering the top of the model. The scan itself is accurate, so no other surfaces should be altered—just add that extra geometry so it sits flush with the existing bottom, then return a printable file.

You’ll receive:
• the raw scan (OBJ)
• a couple of reference photos that show the style and approximate proportions of the "hat" I’m after

Your job is to:
• model the hat in place, making sure it follows the contour of the current top surface
• keep wall thicknesses and overhangs 3D-printer friendly
• deliver the final, error-free STL and the project file from whatever software you use, so I can make tweaks later if needed

I don’t have exact measurements, but the reference images will guide the overall look.

Once the STL passes a quick check and slices without warnings in Creality Print, the project is complete.