MadArtBot: Designing 3D Things

So, you’ve probably noticed that we at Mad Art Lab have been playing with 3D printers. Lots of fun, these things. You can take designs on your computer and print them off as actual, physical objects. How cool is that? But you might be thinking to yourself, “What could I possibly want to print with one of these things?”

If you just want to find something cool to print, check out places like Thingiverse, where people upload their designs for others to use. Tons of stuff there, like RC Koopas, TARDIS salt shakers and Lucky Charms sifters. Yes, really.

But what if they don’t have what you want? What if the thing exists only in your imagination? In that case, you have to design it yourself. Fortunately there’s an app for that. Actually, there’s a whole pile of apps. The ones I’ve used most are Blender, Art of Illusion and OpenSCAD.

Most 3D modeling apps use CSG (constructive solid geometry), which is a fancy way of saying “making complicated bits out of a bunch of simple bits”. There are other modeling techniques but CSG can usually do what you need. For example, you can take a cube and a sphere and mush them together in 4 different ways:

And you can stretch, squish, rotate and move around the bits to make all sorts of things. Like, say your brother-in-law (you know the one I’m talking about) twisted the knob on the dryer too hard and broke it. You could use one of these apps to design a new one like this:

Now, like I said, there are lots of apps you can use to make designs like this. Me, I like to use OpenSCAD because it’s geared toward code geeks. See, when I look at a dryer knob, I see something like this:

No, wait. This:

Most apps, though, have more of a WYSIWYG interface, where you drag around bits and pieces on the screen and mush them together …which is probably better for all you visually-oriented weirdos. And they tend to look more like this:

The main thing, though, is that you need some sort of app that can export your design to an STL file. STL files are pretty much the standard for 3D printers. Here’s a list of apps that can export them. There’s even a completely browser-based app called TinkerCAD that you can use to make simple objects.

Also, there are a few rules you should follow to make things that printable (especially if you’re using an open-source printer like a RepRap or MakerBot):

• Units are in milimeters. So, if you’ve got something 40 units across, it’s 40mm (about 1 3/4″).
• The Z axis points up. Even if your app says otherwise, design your object with Z pointing up.
• Center your object on the X/Y axes and make the bottom sit at Z=0.
• Avoid overhangs greater than about 45 degrees. Each layer of the plastic goop needs to be drawn onto the previous layer. You can’t draw on thin air. Well, there are ways around that too but it’s better to avoid it.

So to recap, the flow goes: Think of something to make -> design it in a CAD app -> export it to STL -> print it.

Of course, if you don’t happen to have your own printer, you can just email the STL file to a friend and have them print it for you. It’s just like teleporting! …sort of …and without the whole turn-yourself-into-a-fly-monster thing.

Seriously, though, you can do this. There are lots of free apps for designing things, and lots of tutorials on how to do it. And worst case, if you don’t have a printer or even know someone who does, you can send your design to a company that can print it for you. Like the man said, “The future is already here — it’s just not very evenly distributed.”