Invert Existing 3D Relief

I already have a finished triangular STL model whose face carries a detailed textured relief. All I need now is the exact negative of that relief while leaving everything else exactly as-is. Here’s... (Budget: £10 - £20 GBP, Jobs: 3D Animation, 3D CAD, 3D File Scaling, Slicing & Print Preparation, 3D Modelling, 3D Printing, 3D Rendering, 3ds Max, Blender)