I don't believe I expressed well the title for my question so if you believe you can change it for a more suitable title please do so or drop me a comment.
Currently I am starting a 3D game with C# but I don't have a designer yet nor any images or anything or any money to invest on it.
I would like to develop it using some sort of placeholder or whatever to fill the graphics so I can make at least the basics of it and later simply switch for the real thing. What tools should I take into consideration for this job that are non-commercial and/or that won't limit me once I have the game ready to release in terms of paying the 3rd parties for extra resource or whatever?
Should the place holders be actual sample images or can I use for example a ball to represent a body (what will be the impact of it later when I switch to the actual body it self) ?