Resize and Scale 3D Model

I need assistance with resizing a 3D .stl file. ITs an exceptionally simple model that I need the ID of its central core changed, the width of its wing-like stabilizers changed, and threaded holes added for set screws... (Budget: $15 - $25 USD, Jobs: 3D Animation, 3D CAD, 3D Design, 3D Drafting, 3D File Scaling, Slicing & Print Preparation, 3D Modelling, 3D Print Design, 3D Printing, 3D Rendering, 3ds Max)