I have been thinking about how to make a tunnel cover.

Back in the days of the Elan+2 and Europa Lotus had tunnel covers the core of which was made from plastic sheet -- vinly or perhaps ABS about 2.5mm thick I think (?) moulded over the shape of the backbone tunnel. The "ambla"/"naugahyde" trim (very 60s!) and padding was simply stuck on the top. The result was pretty neat.

Anybody know about suitable grade of plastic material I could form to shape with a hot air gun, I though of just trying flooring vinyl but suspect it will return to its original flat shape.

Tridy...

MK use some textured plastic which does indeed bend well with the heat gun and holds it's shape very well when recooled. It too is about 3.5~4.00mm thick.