Printsettings:

 0.2mm
~20% infill (still testing!)
no support needed
use PETG! PLA might be to bridle 

You need a rubber launcher! like this or  this

I'm currently trying to build a rubber toy glider, which can be printed in one piece without further assembly on the small Prusa Mini print bed (18x18cm). 

First tests in winter with rain and wind show that it flies quite passably, although some improvements can certainly increase performance.
I would recommend to use it outdoors only!

This plane is under heavy construction!
I will update the files from time to time (higher version numbers) will leave the old ones for now

Since I don't have much experience in aircraftbuilding, I'm still doing a lot of testing with infill and weight trimming. It all happens by try and error :)
If one of you aviation friends has tips for me, I would be very happy about every hint.

it should go to the limits of the print bed, so the plane has to be set diagonally in the slicer (which is important anyway, so that the first layer direction runs parallel to the wingspan)
you also have to turn of the skirt, as it will not fit anymore.
 

To stabilize the flight I bent the wings up a bit. On the photo you can see that I placed two pencils parallel to the fuselage so that they line up with the rear wings and then carefully heated the wings on the rump and pressed the rump down. The flight got much better. The model is started with a rubber launcher.

bend the Flaps or Elevators at the rear wings a bit up. That's what the small cuts are for.

Testing 20% rectilinear Infill