Best way to create a mould - 3D printing or CNC?

Hello all, I have a general question I'd appreciate your help on please. I want to create a mould (mold in American!) to make cakes in, in the shape of a car. So the mould has to be food-grade which is usually polycarbonate. Using some of the CAD files on Grabcad, I see the following necessary steps:
1. modify 3D Cad file to fill in wheel arches behind the wheels, make air intakes shallower etc
2. can I 3D print the "negative" space to make a mould directly in polycarbonate?
3. or do I print the negative space in silicon, have a car cast, and then make a food mould?

Your design and manufacturing experience would be appreciated.

Ideally I'd like something like this, plus wheels, that I can make a top and bottom mould for Aston martin DB11 (thanks to Valentino Les on Grabcad)


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4 Answers

Cake shaped molds are available, and I would start by looking at them:

Aluminum appears to be the material of choice, and all of the designs appear to be formed with a die press or stamping operation.

You could use polycarbonate, but I don't see how you'd bake a cake in plastic. Silicone is a material to consider, but it may depend on the size. A flexible pan is not good for large items.

Something to consider is draft angles. The car shape has to be pulled from the mold, so it needs to have tapered walls (like an ice cube tray). No undercuts, no negative draft.
Since you want polycarbonate, and the CAD data will need pretty steep draft angles, I'd take a look at having the mold vacuum or thermo formed.

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I think you'll want to look at having the shapes formed in aluminum then. Stamping, and casting are both operations which can get you a professional cake pan.

The biggest limitation is cost.
People make sort of generic looking pans now so they are suitable for a wide range of cars. Instead of making a Tesla Model S cake pan, they make a "Sedan" cake pan. The goal being that it be used for almost any sedan on the market.

Once you start making a specific cake pan, you've invested a large amount of money, and will likely experience limited sales as the market for cake pans of specific luxury vehicles may be limited.

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These types of molds are typically made from silicone.

These videos should give you some idea of the process and a source for materials. You'll need to manufacture or find a master. 3D printing might be the least costly method dependent on your skill set.


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I think you're wanting low costing mold making process. My advice is edit the car model to reduce sharp edges and add wheel then 3d print it. Then create the mold by silicone from your 3d printed model.
You can search on youtube for the silicone mold making tutorials.

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