So I have an idea for a simple physical product with a fairly straightforward design that would be made out of plastic. Does anyone know where I can go to get that manufactured? I've looked around but haven't found anything that fits what I'm looking for. Does anyone have any experience with this?
Are you in a big city in the US and need thousands or tens of thousands? Look through Yellow Pages (online, of course).
Just need a handful made? Post your question here: http://bbs.homeshopmachinist.net/ in the General section and make it clear that you intend to pay the going rate if you want to be taken seriously. There are a few guys there who can do small quantity injection molding.
It's a hobbyist board, but people there are quite used to the machinist's equivalent of "I'm a business guy and just need a cheap programmer to implement my idea." They will respond the same way you would to that sentiment.
I've designed a few molds for injection molding processes, but never actually made the parts. Begin with contacting local mold making and plastic injection molding companies and ask if they do small runs. If not, ask if they know anyone who does. Thomasnet (http://www.thomasnet.com/products/plastics-injection-molded-...) has a decent directory of these types of manufacturers. Be prepared to give them CAD drawings of your part (or at least engineering drawings), any manufacturing process plans, product requirements, preferred material (specify a type-ABS, HDPE, LDPE, etc), and probably some other things I can't remember. They usually aren't product design firms, they make molds and then use those to make parts. They may be able to help you select which resin to use, but do not depend on it.
The main thing is the quantity. if you need prototype to small volumes look at quickparts.com. they have a $150 min order last time I quoted a rapid prototype. Next step would probably be Protomold, they do injection molds out of aluminum with high speed CNC machines and can do a 1 day turnaround if you have the money. There's another company I've worked with called Vista Technologies (vistatek.com) out of Minneapolis that did prototypes and then production parts. If you're going to higher volumes you can go to pretty much any injection molder and have them make you parts, some will roll the cost of the tooling into the per part cost. oh yeah, vista will also do urethane castings for low volumes of parts, like less than 100.
I would recommend getting a rapid prototype made out of a material that is close to what you want the final product to be. prototype early and prototype often, what looks good in our heads or on the computer screen often isn't quite right in the for-reals. Use quickparts, vista, or shapeways. Pokeno is still working the bugs out of their 3d printing, give them a couple of months. Shapeways requires you to submit a .stl file of your 3D model. Quickparts and Vista are a little more flexible. I would not recommend a home brew 3d printer, the resolution and the material choices aren't as good. Also, you just want your part not to screw around with a machine.
I've worked as a manufacturing engineer and as a design engineer, product development is what i do for a living. If you would like to talk things over some more, I'd be happy to sign an NDA and maybe point you in the right direction... at least a direction anyway.
If you're still at the idea stage, you will want to prototype first. If it's small enough, you can print it with a MakerBot (Desktop 3D printer for $1200 or so). Alternatively, you could use ShapeWays (the "fedex/kinkos" of 3D printing). Until you actually have production volumes in the hundreds (perhaps thousands) of units, this will be the cheaper, faster, easier option.
The printer. raw material is then 50cents/pound or so, and it basically all goes to use.
It's a kit, not hard to build from what I've seen and heard, but still you have to be willing to spend those few hours tinkering (or find someone else who does).
It takes 20-30 minutes to print a nontrivial object, but it can run continuously for hours, so it's good enough to prototype with and get the first 20 made.
If you want to build some volume product you will need some kind of drawings, get a steel mold, find a place for production, quality inspection, packaging, marketing, sales ... and so forth. As you can see that is not a simple answer.
You can check out quirky.com maybe that is a way to go for you.
Or read this blog indicating the effort you will have to put in place
If all else fails, pick up a copy of the book Fab, which is about personal fabrication -- ie "printing" plastic and such with your computer. I read it about 4 to 5 years ago and at that time a lot of the ideas were pretty cutting edge and not really available to the public. I bet a lot has changed in that time.
Just need a handful made? Post your question here: http://bbs.homeshopmachinist.net/ in the General section and make it clear that you intend to pay the going rate if you want to be taken seriously. There are a few guys there who can do small quantity injection molding.
It's a hobbyist board, but people there are quite used to the machinist's equivalent of "I'm a business guy and just need a cheap programmer to implement my idea." They will respond the same way you would to that sentiment.