I'll agree, the clay sounds like a quick and easy method to add some weight.
Plasticine would work too...if you can still get plasticene?
I'm having good luck with paper clips.
Can't get much simpler than that.
You could also use staples (from a stapler).
Add them, one at a time, until the plane is balanced in flight.
If you plan ahead, you could position and line them up nicely,
and theres plenty of room to add many (as needed).
I'm adding the extra wing root part to all the kits now...
except the Tutor jet.
I have decided to add a separate part, that is installed on top of the wing (to the fuselage).
There is enough room on this particular model sheet, and it works really well.
Its a little bigger, and cuts out easily.
