3D Print CAD Design for Oblong Tube

I need a CAD design for a 4.5-inch oblong tube intended for 3D printing. One end should feature a 3/4-inch NPT thread for a standard pipe fitting, while the other end should be open and smooth. Specifications: - inside diameter 4.5" - Length: 14 inches - Shape: Oblong - a funnel shape down to the 3/4 fitting - End 1: 3/4-inch NPT threaded for standard pipe fitting - End 2: Open and smooth - Wall Thickness: Approximately 3/16 inch Ideal skills and experience: - Proficiency in CAD software - Experience designing for 3D printing - Knowledge of NPT threading and pipe fitting standards Please provide samples of similar work.