After designing my business card glider, I decided to try an all 3D printed design. Taking a lot of inspiration from exosequitur's collection of gliders, I came up with this smooth gliding design that just fits on the bed of a Prusa Mini+. It prints in a little over an hour and is easy to assemble without clamps and without supergluing your fingers to the glider. The long neck and the thin wings are flexible enough to absorb energy on impact to avoid breakage, even when printed in PLA. (Flying over cement or asphalt, though, is not recommended.)

Printing
To get the right weight distribution, print in PLA with 0.2mm layers, 3 perimeters, and 90% infill. 100% infill might be slightly better (more nose weight) but you run the risk of a messy print if you are over extruding at all. Also make sure the top and bottom infill is aligned parallel or perpendicular to the wings. I've provided the STL file already oriented at 45 degrees to fit on the bed, so the typical default 45 degree infill orientation will already line up parallel to the wings.

Assembly
First dry-fit the assembly before gluing:
The wings fit into the underside of the fuselage, with the thick edge of the wings facing forward. The should press in flush with the bottom of the fuselage. The tail vertical should fit snugly into slot at the rear of the fuselage. Disassemble before gluing.

Gluing:
Place a few drops of superglue in the wing slot on the underside of the fuselage. Re-insert the wings, making sure the thick leading edge of the wings are towards the nose. Also place a few drops of glue along the seam between the two wings as shown in the second photo. Flip the glider over and place a few drops of glue along the seam between the wing base and the fuselage as shown in the third photo. Lastly, place a few drops of glue in the tail slot and insert the tail vertical.

Trimming for Flight
Depending on the exact weight distribution you end up with, your glider will either want to climb and stall (or even loop), or it will dive into the ground. If it wants to climb and stall, bend the trailing tips of the tail horizontals downward ever so slightly as shown in the last photo. Even a barely imperceptible bend will make a big difference in the flight trajectory. If the glider tends to dive into the ground, flex the tail tips upward. Make adjustments incrementally until you get the flight you want. (I'm a fan of the long, straight, soaring flights.)

CAUTION: Gliders can have looping, unexpected flight paths where they might hit you or someone else quite unexpectedly. I've had to duck a number of attacks while trimming various test models. Wear eye protection and don't fly in crowded places.