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What's a good cost effective way to make a large plastic body/case? Answered

I'm working on a kitchen countertop type of device that would be similar in size and appearance of a large coffee maker.
I plan on making around 50 of these for an initial run. Cost is a factor to prove that a profit could be made while not outsourcing the work involved. My goal is to keep this cost below $30 each part, but could go as high as $50.

The body will need to be hollow, and has initial dimensions of 18"x12"x8". It does not need to be one piece, several pieces that can be assembled is actually ideal.

Here are a few options that I have looked at as well as my concerns...

-Injection molding- I worry about the setup costs for equipment let alone the space needed.

-Resin casting - I worry about it being too brittle and effectively making workable molds for assembleable parts.

-Resin coated foam - I worry about the look of quality as well as the cost of foam.

-Vacuum forming - My main concern is the cost of sheet material.

I'd appreciate any input, whether it is to add more ideas or to address concerns that I have.


FORGET injection moulding in 50 offs ! The tooling costs will kill you dead.

Whatever you do you're stuck with needing a tool to form on, but, unless you need to really crank these things out, I'd use a fibre glass reinforced polyester.


Depending on the actual shape of the product AND the materials you need to use :

Vacuum form. If you make the pattern there are a lot of companies out there that can do it fairly cheaply for you in small runes.

maki8nf the pattern is the costly bit BUT it could be MDF for a short run.

The last time I did this was to make a small tool case for an exam student - Yellow pages found a vacuum forming company just down the road in an industrial unit that did it for the cost of the materials in about 30 mins.

Talk to them about the pattern and what it needs to look like.

There are instructables here to build your own vacuum former if you search.

Tends to look naff though - especially for a kitchen type consumer appliance.

Depends on the skill and precision a lot of hard suitcases are vac formed - that's what the company mainly did.

With the right materials and machinery very good results that compare to injection moulding can be produced.

Admittedly a lot of amateur vac form looks DIY but that's a lack of skill

As does a lot of fibre glass work etc.

How complex is the surface? Have you considered crowdfunding to help you develop prototypes? It sounds like you could set a pretty low goal and then be able to afford a more expensive, but easier, method

There won't be a lot of detail on the surface, just cutouts/voids where I would like to add a small faceplate for a touch screen. This I can cast easily, as it is small, and snap it on to the main body. The edges will be rounded with a large radius and the face will nearly be completely round.

I am actually putting this together for a kickstarter project. We have set a minimum goal of making 30 items that would be targeted to retail around $350. The project itself will be break even on materials and equipment costs on a $10k goal. We could go for a higher budget, but it would really defeat some of the goals of the project, like demonstrating a profit could be made without outsourcing, and having it production ready.