May have been thought of before but can find nothing on this forum. When using cleco?s in fibreglass I find the don?t grip very well. Found this especially with the cooling duct. Used an old offcut from the wing ribs. Cut a slice about 3/16? wide. Marked it same dimension along the length, centrepunched then drilled #40 each square then cut the squares with tin snips. Gives a handful of small square washer which when used on the back of the cleco?s improves the grip substantially in fibreglass. Worked for me.