See through materials are available in dozens of types and grades. Materials such as acrylic and polycarbonate are available in both Transparent & Translucent grades.

Transparent = Images can be viewed through sheet (like tinted glass)

Translucent = Light & Shadows can be seen through Sheet.
There are even high-performance fluoropolymers such as FEP that have excellent clarity. For more information on see through materials, contact a Professional Plastics Salesperson.