Firstly, cost. If we say that this is your one-off project is one-to finalize the bumper on your car, it makes no sense to spend on the material amount in excess of all other costs. For example, we present the architectural value of plasticine – from 5 to 8 cu per kilogram of material. Second, the “complexity” of the material. Try the usual mold of the clay model of the small of your bumper. In 90% people there even at this difficult stage. And do not think that with a large surface to work easier. Third, the material’s surface is easy to strain.
It’s a shame when ready to eat of the matrix surface something falling from the top and left a dent that needs to be re-communicate to the ideal. Even more insulting, when renting the matrix breaks up the layout, and the matrix failed. This will bring you back a few weeks (at best) ago. Fourth, the amount of time. Hides surface plasticine layout of course not. The whole area will need to bring to an ideal state with special scrapers and spatulas. Without years of experience with this material, the process can drag on for an indefinite amount of time (by the way, he might not finish).
Polyurethane foam. Judging by the number of articles, much loved and respected by all the material. Advantages in this material not found me. Let’s talk about the disadvantages. First of all, price.