RE: Gentle Lady Removable Wingtips Option
I made my electric Gentle Lady with the removal wing tip option and did what BMATHEWS describes, the music wire into tube spar extension, small dowel aligning pins all held together with elecric tape. Never had an issue, had heaps of flights now.
Wash out is not a problem, just build it into the wing tips.
Make it as per the instructions, with small aligning pins, all good.
Remember weight is an enemy to model planes