ORIGINAL: gcb
Back in "the day" when model builders used everything they could, some of us used Ambroid tube caps (which at that time were screw eyes) for that purpose. The empty tubes themselves became wing tip weights.
George
George --
You're starting to date yourself now.
In my diminished mental capacity (well, maybe it's as good as it ever was), I had forgotton about the screw eyes. Nothing like building with orange!!!