Thank you Phil
My model isn't scratch but almost ! It's old vacuform kit from Air Press production.
you can see with this picture : vacuform plane
The molding has been accomplished by using a vacuum table to draw a heated sheet of plastic into or over a mold. While some vacuform kits lack fine detail, others are well molded and contain panel lines, rivets, textures and complete interiors similar to injection-molded models. Vacuforming has also been used to produce model boat and ship hulls.
It's the same presentation for my radschlepper