I've been having fun with this little 3 channel RC P51 from DEERC. Flying with the nephews, I wanted better slow flight characteristics and less wing drop tendency. These fixed 15 degree flaps did exactly what I wanted.
My printer has a .6 nozzle on it so I made the flap .6 in thickness.
For installation, I put blue painter's tape on the wing to protect it and then used carpet tape to attach the flap to the painters tape.
The author marked this model as their own original creation.