I had some old parts, and a couple of new ones in the parts bin, so I decided to use them to make a hovercraft - or rather a glidecraft. It is more like an air hockey puck than a true hovercraft.

The orange part of the body I printed from Esun PLApro. The white bits are Hatchbox PETG.
The blue part is hobby carving foam that I laser-cut into shape. The laser cutter is not set up for the 25mm thickness that I used, so it melted the foam - which ended up pretty neat looking. Next time I will probably turn down the laser power.

One good thing about this build is that I was finally able to use the Racerstar Dark 18A 4in1 that I purchased a little less than a year ago. Whoever thought that putting bat+ and bat- on the M2 mounting holes should be switched. That is why the esc is not in the stack. It is off to the side so each mounting screw can have its own electrically-isolated PLA hole to screw into.

The front two motors are so old, they don't have a link any more, they are SunnySky 1104 4000kv which make the distinctive growling sound of the first quad I ever assembled. Those bells are really loose. It is amazing how far drone motors have progressed in the last year.

There is still a lot of motor tuning to do, but so far it has been fun to "fly".

update 1: I was flying it in the lake (it floats) and a big wave swamped it. I lost one of the two front motors and the VTX. That was my last pair of those old motors, so now I have 4 of the 1106 Emax.

update2: Originally, I had the ATX03 up front with the camera, but with its small size and thin board it overheated (black sparkles) so I moved it back to between the ESC and FC to get some active cooling from the horizontal props. The VTX holder has a piece of thermal compound under the board, which should even out the heat on the back side. The place where I am flying it has some high-power lights that put out significant EMI, so I have switched out the dipole antenna on the ATX03 for a u.fl AXII. I have been impressed with the AXII on my 5" build, so hopefully it will work well in this environment.

The forward drive props are deliberately larger than the downdraft props. I need enough lift in the open plenum to keep it slightly above the ground, but not so much that it lifts off. I still get a little too much lift-off, so in the next version I am planning to angle the downdraft props towards the back of the craft. I'll carry extra props the next time I take it out so I can vary the downdraft vs forward thrust.

Originally, it had square edges on the bottom with a neat melty-look from the laser, but it would catch on the smallest floor imperfection, so I sanded a radius on the bottom - which seems to have improved its speed and handling.