A completely new Ultralight Glider design inspired by the YF23 fighter jet concept and using lessons learned from my previous Ultralight 2gram Glider:

https://www.printables.com/model/430012-ultralight-2gram-glider-print-in-place

(also check out my glider spaceship: https://www.printables.com/model/462466-uss-enterprise-1701-f-print-in-place-glider )

While this glider can be hand thrown, it flies much better with a rubber band launch and performs more consistently outdoors compared to the Ultralight 2gram Glider. Both designs should fly well and use only 2 grams (less than 1 meter) of filament and take just 15 minutes to print. Print a squadron of each and have a blast.

Instructions:

Print 0.2mm layer height, Infill angle to align with airflow (front to back of the plane)
Let cool, pry off the printer and turn it over (the smooth print-plate surface is the top)
Turn over, bend the V-Tail up anywhere between 45 and 90 degrees
Give the flaps on the main wing a slight bend up. Slow flights work better with steeper angles, and fast launches work better with a softer angle.
Hook a rubber band under the front rubber band catch.
Pull back using the flat area at the rear.
Let go and enjoy

Special thanks to @becki05_321509 for designing a launcher to make rubber band launching easier - find the great model here:

https://www.printables.com/de/model/501691-slingshot-for-airplanes