Ever wanted to 3D print a real life building? It's actually pretty easy and this tutorial will summarize a few good forums and instructional sites on how to do this. Here's the general workflow:
What you will need:
A computer to run Google Earth, Google Sketch-Up, and Replicator G. All are free downloads.
Makerbot or similar 3D printer. If you don't have one, fear not, you can always send your file to Shapeways, Ponoko, or use one at TechShop.
I-Selecting and Downloading a Model: using Google Earth to find the building you want to print.
II-.skp to .stl (Sketch-Up to Rep. G): bringing the model into Sketch-Up to make some changes and exporting it as .stl file
III-Getting the File Ready for the Printer: Bringing the .stl file into Replicator G and exporting G-Code to Makerbot
Step 1: Selecting and Downloading a Model
1) Download the latest Google Earth. It may be possible to do this through the browser version in Google Maps, but I'd rather use something more stable. Plus Earth is so cool, just so cool.
2) Enable 3D buildings.
3) Find A Building. Anything that highlights blue when mouse-over can be found in 3D Warehouse, which is the repository of user-made files associated with Sketch-Up. Click on a building and then the picture of the building to take you to the page in 3D Warehouse. Not all buildings used in Earth are downloadable. For this tutorial we chose Taipei 101.
4) Download the Model (.skp). Happens to be in this case, the Taipei 101 model used in Earth is not downloadable but a quick search of 3D Warehouse yielded some great models that are. You can tell which ones are or are not by the blue "download model" drop down. You can always use 3D Warehouse without first going through Earth, but that's no fun, usually. Other models in other formats can be found on Thingiverse (great for .stl files) and on Autodesk's 123D.
**note: some buildings simply won't make good 3d prints because of all the terrain used to make the model. Whatever is highlighted in blue on mouse-over will also make its way into the 3d model and may prove difficult or impossible to print.
Step 2: .skp to .stl (Sketch-Up to Rep. G)
1) Download and install Sketch-Up.
2) Download and install an .stl export plug-in. Un-modified, Google Sketch-Up won't export an .stl file. This is unfortunate as most 3d printing software packages prefer this file type. Thanks to some great people there are easy to follow steps for solving this problem. I use this one: http://www.guitar-list.com/download-software/convert-sketchup-skp-files-dxf-or-stl. Follow the steps on the site and then come back.
2) Open the .skp file and clean it up. This is going to be different for each model you find. Most of the models that come from Google Earth are going to contain some sort of "earth" that we don't want. Meaning, a 2d platform on which the building sits that has roads, sidewalks, hot-dog carts, trees and parked cars. Usually, this just makes the 3d printing services angry. Some models will actually contain 3d terrain that can be used in some cases. Its going to take some practice, but suffice it to say, the best thing to do is to get rid of any 2d components. Paper-thin trees made by two bisecting 2d textures are gone. The satellite image is usually good to get rid of as well. Once I have something looking clean, I make sure there are no holes...meaning the base I just deleted revealed that I now needed a rectangle to close up the building. I also noticed that one of the circle thingies on the side had a crack in it...delete and redraw. To check for "water-tightness" I use AutoDesk's Meshmixer. This is also a free download and has some excellent auto-correct feature. Sometimes it is necessary to right-click elements (bounded in red) and "unlock" them. Save-as so you can always come back and make edits.
3) Export as an .stl file. Select the entire model and then go Tools-->Export as DXF or STL. Save as units isn't crucial unless your 3d printing service or software doesn't have a scaling option. Make sure to be consistent. I've had a lot of folks want several buildings in the same scale, and this is where this can matter. Rep G has a mm to inches scale, but in this case, this is more handy. This model is probably in Meters or Feet. I don't really care about the scale in relation to anything other than itself, so I'm picking meters. Save as .stl.
Step 3: Getting the File Ready for the Printer
1) Download and install Replicator G.
2) Import the newly created .stl file.
3) Scale, Move, Center, Build. Once you import the file, you may not see anything, or see all yellow, or see unicorns and flying hammerhead sharks fighting over rainbow seas. This is not unusual (the first two possibilities). It just means the .stl file isn't centered and is gigantic, perhaps even true to life size (figure 4-1). First thing to do is to "put on platform" and "center" (figure 4-2). Once this is done, you can start scaling. If you picked the units to export correctly from the last step, your .stl should be exactly the size of the building in real life. Want a 1/100 scale model of it? Type .01 in "scale" and done (figure 4-3). **Remember that Rep-G doesn't track the last input, so the scale is a multiplyer enacted when the button is pressed and not a reflection of the actual scale. For example if you put in .1 and clicked scale twice the field would still say ".1" but it would be .01 times the size (.1 x .1) of the original. If you picked wrong, you can always adjust. Rep-G doesn't have any way of telling how big the .stl is...you have to guess by the size of the platform (in blue with white grid) matching up to the replicator build platform give or take. Super-lame. Most of the time it's a simple factor of 1000 (meters to mm) but just in case here's a handy tip: 1m = 3.281ft and 1ft = .3048m. If you are still seeing a unicorn-shark melee, you might want to question the decisions regarding temperance you've made up to this point in your life.
4) Generate the G-Code. I use the default for most of my buildings. Some do quite better with .1mm layer height. 3 shells also is a good idea when you've got thin structures...in this case, default is fine. Once the G-Code is done, its time to estimate it. G-Code-->Estimate. This gives you a clue if you've got something good going on. Too long and your .stl might need some more work in Sketch-Up. Too short and...it has never been too short for me so I don't know what to do. Satisfied, click the G-Code tab and change the build plate temperature from 110C to 115C (figure 4-4). Standard operating proceedure. Save the .s3g and get ready to print.
Impress your friends by printing out their apartment building and putting it in a diorama with Godzilla.
Or better yet...turn this into a chocolate.
Let me know how it goes,
The model was done at at .27mm res with 1 layar wall thickness. No raft, no support. Layer time was adjusted to minimum 15 seconds so the tower wouldn't slump at the highest levels.