As someone who supports 3D printing as an amazing tool with vast applications across nearly every industry, I also find that its use as a buzzword has not been entirely beneficial the public and new designers. No one should underestimate the importance of prototyping, but the right process should be chosen. I’ve seen a shift from people saying “I need a prototype” to “I need a 3D print” and it doesn’t always fit. This primarily comes from startups and inventors who aren’t familiar with prototyping. Even in school I saw a shift that was moving almost all prototyping to 3D printing. As always we see the bright shiny thing and drop everything else for it rather than seeing it as just a single tool in a large tool box. With that in mind, I put together a few examples of when 3D printing shouldn’t be used.
Large mostly flat components.
I’ve had clients try to tell me we should just 3D print a flat part. Often these parts have very few features on it or barely fit on the larger print beds. I’ve done it and it’s either super expensive or there are warping issues that make the part less than ideal. If you can make it out of wood or sheet plastic then it’s usually easier and cheaper than 3D printing. Even sheet metal is hard to replace with 3D printing.
Organic & Other Materials
While I highly recommend using 3D printing for fit checks any time you can, if you are looking to have working prototypes that might be made out materials besides metals and plastics, prototyping in those materials is often better. Things like wood, leather, and paper come to mind especially.
Prototyping any kind of softgoods, whether a bag or clothing, requires textiles, not 3D printing. Even the flexible 3D printing does not adequately provide the material needed to even prototype with. It does, however, work great for custom hardware and components that can be used with softgoods.
A side note on hardware and other off shelf components. This one might be obvious, but it isn’t always. I’ve had clients ask me to 3D print components that would be cheaper to buy off the shelf before. So, remember that almost anything you buy off shelf is cheaper to do so that make your own. Sometimes it isn’t the 3D printing that makes it more expensive, but the design time to create the 3D model and then 3D print. Once you add a couple hours, plus vendor communication, plus cost of making it, it can be costly. For these reasons, I almost always source off-shelf components when prototyping.
This list is short because there are very few applications where 3D printing isn’t a great choice for prototyping mechanical designs. This is for fit, function, or aesthetics. The technology is ever changing and I’m sure one day we’ll see the ability to 3D print everything. For now though, there are a few remaining ones you can’t, or shouldn’t, 3D print.