Designed and built this little beast with my Son just recently. While it doesn't fly like a plane, it does hover 2-3 cm off the ground and is really fast.

Video 

Printing

Came out great using PET (0.2mm layering, 2-3 perimeters) and I'd think PLA would too.

Parts

• "All in One" Flight Controller (AIO-FC) that runs 2-4S and has a mounting size: 25.5*25.5mm. If requested, I could add more mounting holes for other FC sizes.
• Battery Eliminator Circuit (BEC) to allow you to route the power from the battery to the flight controller while also providing some isolation from it. Ideally you'd also want it to have its own 5V regulator so you can connect the receiver to the BEC rather than to the FC.
• FrSky R-XSR Receiver, but realistically any old receiver will do.
• Emax RS1108 motors (Ducts) and BetaFPV 1105 motors (Lift-Fans). Obviously you could easily substitute for what ever you have on hand so long as they fit on the motor mount and can run off 2S LiPo. Would recommend that for the lift fans you use motors that are not too tall as this will place the propellers closer to the ground. Hence why my motors are two different types. Just so you know, the last digit in the motors size denotes how tall it is.  Example 110(5)
• EMAX 3" Tri-blade Emax racing props for the Ducts.
• HQProp 65mm Tri-blade propellers in the Lift-Fans.
• 2mm thick neoprene craft sheets. This is used to make the skirt around the inside of the frame. Just stick on using (thin) double-sided tape as you may have to replace bits every so often.
• 2-4s LiPo of 500 to 1000mAh range and XT-30 Battery connector. 
• Keep the LiPo as far forward as possible to help keep the nose down while under high throttle. Otherwise the nose can lift up, causing the craft to flip.
• Alcohol, liberal amounts to sooth the finger burns your going to have from soldering all those small motors on. (Evil laugh)

Setup

Once everything is printed, set up the hovercraft as you would a normal quadcopter. Except lower (or zero) the Pitch and Roll (PID) gains, so it wont misbehave. Obviously, this assumes that the builder has some knowledge of electronics, quads, and the software related to RC craft. 

Updates / Notes 

• The main body has holes, slots and channels that can be pushed thru if needed for wiring, zip-ties and such not.
• The Lift-Fans are not intended to make the craft fly, but rather create a cushion of air that's trapped under the frame.
• Please keep in mind that this craft can "work"  on just about any flat surface. That being said, small stones, leaves, and sand will wear out the lifting fans as they're held very close to the ground.
• 3-1-2023, Forgot to add the “Lower Mounting Bracket” with the original posting. (corrected)
• 3-5-2023, added more pics detailing the wiring and layout, as well as a short video. Sorry about the video being only a few minutes, but my son was filming, or at least he thought he was. The basketball court we were using had a lot of small leaves which got stuck in one of the Lift-Fans.
• 3-5-2023, Added a thicker lower mounting bracket that prints laying down. This should print a bit quicker as well as have the layer lines going vertical thru the part.