3D Product Design for a Sports Accessory

I am designing a cart for a sport called disc golf. I need help taking my idea and turning it into a 3D design . I also need help with material choices for the frame and some simple design advice. The cart will be on two 20 cm wheels and have a double rectangular frame that is about 60 cm wide and 120 cm tall with a handle on top. The outside frame will likely be metal or plastic and the inside will also be that chosen material but slightly smaller and have thick nylon or canvas wrapped around it. The smaller frame will rotate from a center point at the top and bottom so the back becomes the front and vise versa and can be locked in place. The front will be filled with 2 columns of 10 slots to hold discs and the back will be custom sized pockets for accessories. So far I have just a rough drawing. I am not exactly what skills I am looking for but good English communication is mandatory.