Before you smash the “Post Comment” button with the fury of Zeus himself, we’re going to go ahead and say it: if you want to build a decent quadcopter, buy a commercial frame. They are usually one of the cheaper parts of the build, they’re very light for how strong they are, and replacement parts are easily available. While you could argue the cost of PLA/ABS filament is low enough now that printing it would be cheaper than buying, you aren’t going to be able to make a better quadcopter frame on a 3D printer than what’s available on the commercial market.
Having said that, [Paweł Spychalski] has recently shown off his 3D printed FPV racing quadcopter frame with some surprising results. The frame ended up being surprisingly stiff, and while the weight is a bit high, it’s actually lighter than he expected. If you’re looking to build a quad with the absolute minimum of expense his design might be something to look into.
Of course, [Paweł] is hardly the first person to think about printing a quad frame. But he did give his design some extra consideration to try and overcome some of the shortcomings he noticed in existing 3D printed designs. For one, rather than have four separate arms that mount to a central chassis, his design has arms that go all the way across with a thick support that goes between the motors. The central chassis is also reassuringly thick, adding to the overall stiffness of the frame.
The key here is that [Paweł] printed all the parts with 2 mm thick walls. While that naturally equates to longer print times and greater overall weight, it’s probably more than worth it to make sure the frame doesn’t snap in half the first time it touches the ground.
Beyond the printed parts, all you need to assemble this frame are about a dozen M3 nuts and bolts. Overall, between the hardware and the plastic you’re looking at a total cost of under $5 USD. In the video below [Paweł] puts the frame through its paces doing some acrobatic maneuvers, and it looks like 5 bucks well spent to us.