There are many sources of 3D models, including free models on the internet. You can also build the 3D model yourself, purchase models, or contract with an independent modeler.
Building 3D Content Yourself
If you are modeling organic shapes, Strata Foto 3D CX 2 is a good choice for capturing the textured 3D geometry. Anyone with a good digital camera, the right software, and a willingness to spend some time can create excellent 3D models.
The process involves taking several high-quality photographs of the object, masking out the background, and then importing the images into Foto 3D to create the 3D geometry and texture. In some cases, the 3D geometry may need to be fine-tuned in a 3D application like Strata Design 3D CX to improve the overall look.
For man-made shapes, your best bet is a 3D modeling tool like Design 3D CX. You can place a picture in the model, trace the basic shape, and then applying extrusions, lathes, and other operations to bring the 2D picture into 3D.
Buy 3D Retail
A surprising number of real physical products have already been modeled, and care available for purchase. If the model is not available in VRML2 (VRML97), Alias Studio, or K3D, you may need to use another application to convert it to a file format that Live 3D can read.
Contract for 3D Modeling Services
Many 3D artists will contract to create models. If you contract with someone, you should require that they deliver you a complete, working 3D tour created using Strata Live 3D CX, not just the VRML97 files. That way you will know that the 3D model was created using appropriate web modeling techniques (textures use standard formats, polygon count is reasonable, etc.).