To reduce color change time in modern powder coating systems, vendors evaluate multiple booth-canopy materials. Recommending one material over another is not appropriate here. A better approach is to help you understand the impact of material selection on your system's performance and to provide you with questions you can ask your vendors.
Powder attraction to the booth walls. Whether the booth is made of double-wall materials, solid plastic or composite dielectric material, the electric field will penetrate it. There is no difference in the way double-wall ("sandwich" construction) material works in the presence of the electric field compared to a solid or composite material. However, if there is a metal support structure near the outside booth wall, the electric field will concentrate on it, resulting in more intense powder deposition on the inside of the booth in that area. Make sure there are no metal hardware or support structures touching or near the booth walls.