So there's a couple of things you need, depending on whether you print it yourself or go down the library
1. 3D Modelling software to create the model. I personally use
Blender, but it's not really suited for CAD, it's more for animation. Other options include OpenSCAD, TinkerCAD, SketchUp. It's not really an 'automatic' process to model from an image, so expect to spend at least a
couple of hours figuring out how to use it.
The other option is to pay someone on
fiverr or the like to create the STL file for you, which depending on your 3D modelling experience might be the way to go.
2. Take the STL file you created in the 3D modelling software and take it down to the local library on a USB key. Can't remember if it's just Hume but lots of libraries have 3D printers free to use. If your local library doesn't have one, there are a few businesses popping up now that will 3D print your design for a small fee.