Helicopters are complex machines. They require high quality parts that are strong, lightweight, and accurate. Those are terms typically not associated with parts made on home 3D printers.But could they be?We all know home machines are getting better, but could you actually print a working helicopter on a home 3D printer? The obvious place to start is the blades. They must be thin, light, smooth, and strong. If you can't print blades, you can't make a helicopter. So can you?Well, spoiler alert: you can. But do they actually work? Or do they fly apart when they spin up, or generate too much turbulence to actually fly? See for yourself: http://www.youtube.com/watch?v=qXlUSWrVzysPrinted on my Ultimaker 3D printer, using Netfabb "Ultra" (0.08mm) profile, 100% infill, 100% speed, no raft. Takes about 26 minutes per blade.The helicopter is the "JXD 340", or sometimes the "Drift King" because unlike most cheap helis, it can fly sideways. Its a pretty awesome toy for $30, and much better than most cheap helis I have seen. Personally, I recommend it. Have a link: http://www.amazon.com/Indoor-Infrared-Control-Helicopter-Gyroscope/dp/B004OGBNJ8/ And no thats not an affiliate link, I just think those toys are sweet.SAFETY NOTE: I recommend PLA because it sticks well and works well with small layer heights. HOWEVER, PLA is brittle, and when these blades break, they tend to shear off and send a sharp piece flying. The pieces are light and it may not be an issue, but you have been warned. If you're about to crash, cut throttle power so the blades stop spinning and the amount of energy put into them is reduced. They've survived plenty of nicks on things, but if you crash under power they will break. Ultimately though, I am not responsible. Print at your own risk.EDIT4: Now with source files! Solidworks 2012. Both blades are there. Suppress the last "body delete" command to show the other blade. Unsuppress one or the other when saving STL Files. Use the coordinate system I added when exporting (in STL options. might already do it by default now)EDIT 3: Added some new smaller blades. They don't have as much lift but the heli seems to fly faster. Interesting! They are 2A and 2B, and print in about 17 minutes apiece. Also, sorry, this is getting messy, I should probably re-write this section.EDIT 2: Added pictures of a blade as printed, before being removed from the bed. Its actually a slightly smaller design I'm working on, but it demonstrates the orientation. I will try to get higher quality pics soon.EDIT: STL Orientation is now correct. In case there is any question: Print the blade upside-down from the flying configuration - you'll see that there is a slight flat on that side. The overhangs seem to work OK with small layer heights.There's an A blade and a B blade. A goes on top, B goes on bottom. Unscrew the old blades and screw these right on.Aside from yanking off some fluff with my fingers, I didn't so any secondary operations on these things. Just print and go.Print these with small layer heights (I used 0.08mm) and blast it with a fan to keep it from deforming while printing. They're only 0.025" (.65mm) thick, so they want to deform. I used PLA, no raft, printed on blue tape, and most of the time they stick well enough to print. I have no idea if this would work with ABS. Also I'd print these one at a time to avoid stringing.If you buy one of these helis, pick another part and try to 3D print it. If we can slowly replace all the parts on this thing with 3D printed parts, we will have eventually created a home 3D printable helicopter! Let me know if you do - mark your part as a derivative or something so we can keep track!