Polyurethane foam... Sounds like a good material, can you add more when you take too much off in the process of sculpting? I guess you are right about the weight.




I think I need ribs for this, just like you mention the symmetry problem. 

I will add more pictures as I go, obtaining the design in 1:18 scale took a month already and I think I got it, but need to clean up the pictures in photoshop before sharing. 

Thanks again!

Your patterns don't need to be light, they will be removed when you replace them with the carbon fibre ones? Your suspension is certainly not going to struggle with that sort of weight, it's a 1300kg Porsche! 

In any case, I have never liked working with clay, there's a real art to that technique that I just never got the hang of. Certainly not easy. Polyurethane foam is my go to. Whether you need ribs or not depends on what you are actually doing and how good you are at sculpting symmetrically. Ribs can give you a basis to get things symmetrical from side to side if you are doing quite big changes, but if you are simply widening the wheel arches 50mm or whatever then it's quite easy to do without the ribs and just use measurements.

Is this your first attempt at pattern making? If so, you may wish to experiment on a smaller scale first, this is certainly not an easy place to start.

Hello everyone, I am looking for some help.
I want to take my Porsche car (987S), add some clay like material to the existing body and form widebody panels and then continue with mould preparation for carbon fiber. My question is: do you have any suggestions on what materials to use to add on the car in the first process of widebody positive moulding?

In design studios they build the car from brown/reddish clay. However, adding clay to the existing body may be a bad idea for many reasons, there is quite a lot of volume to add which translates into a lot of weight, it puts strain on the suspension and may just not stick. I am wondering what is the best technique, for example using some light wood ribs over the existing body, then filling the gaps between the ribs with foam and adding skin on top. But this would require a lot of time, and wouldn't be easily adjustable. I was thinking about creating volume from some hollow objects, for example scrunching some hydrophobic film (like paper) and adding plaster on top to create a shell of the desired shape.

But I really don't know what is the way to go and I would appreciate your input! Maybe you know of some lightweight materials that are good for this purpose?

Thanks!