Following @SpiritusRaptor 's post on flaps, I thought why not share my flap design and give anyone who wants it an easy solution for adding working flaps to their planes. Although I understand this is not the most elegant design when it's extending, it provides a very good looking but simple, one rotor solution ,to adding flaps. On the left side is how I would set up the flaps in a typical wing situation, and on the right side is a ploppable flap you can take for yourself. It is mir rror-able although you must mirror it *BEFORE* you nudge away the rotor and the "cam shaft". The crucial thing is to not try and move the cam shaft too much forwards/backwards or upwards/downwards, moving it into the body of the plane does not affect the motion of the flaps.

When placing, nudge the wing downards, and then place the assembly on the side of the plane under the wing. Then nudge the rotor and the cam shaft inwards, and nudge the wing piece upwards. Enjoy!

*side note* if you do end up needing to move the cam shaft or the due to an unsuitable body, Moving the "cam shaft" sideways away from the rotor makes the flaps move lower and moving the cam shaft downwards away from the rotor makes the flaps move further out in a circle. The vice versa for those two points applies.