Your knowledge of basic economics is appalling.  Tell me which executive order or law that Biden signed pushed gas prices up - I dare you!

Sorry about the dup above. Note that your reflection approach is used by some “HUD” mfrs. Search Amazon for “HUD Film” to find the semi-reflective film to use for such a method.

Why are we hung up on the cardboard and duct tape? Clearly, this served as an inexpensive proof-of-concept. You can make as many configurations with cardboard and duct tape as you like, then choose the best one and use the cardboard as a template for more durable and presentable materials.