one of the challenges is to make functional rudders and planes.
The kit rudders are small, and do not lead themselves to drilling etc.
I found a quick and easy way to create my own rudders.
I have some plasticine (often used for moldmaking).
I pressed the plastic kit part into the plasticine,
removed the part so it's negative (of one side) remained in the plasticine,
then inserted a brass rod where I wanted it.
Then I just made a bit of epoxy glue and used that to fill the negative.
obviously the other side does not look like anything, but a bit of filing and sanding gave me a decent diveplane.
since then I also made myself a rudder, since I could not think of a way to extend the rudder axle
in a reliable way.