RE: Sanding edges
Masking tape is a secret weapon for sanding. Protect the sheeting adjacent to the leading edge or wing tip prior to sanding. I use the blue painters tape in different widths for this task.
When sanding wing tips I usually wrap some masking tape over one end of a sanding bar. This wrapped end rides on the wing skin and prevents cutting into the skin.
You cannot have too many different sanding tools.
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