I'm looking for a plastic material in sheet form that I can mould to a (roughly) U shape but with a squared off part in the U curve in the middle.
Basically, the idea is to mould the material around a roof rail of a car to seal around a small box ( say 100mm x 25 mm * 25 mm) that is in a gap in the rail.
After mouldng, material needs to be sun and water proof. and keep the moulded shape once formed.
Can anyone suggest a material and method?