I just finished making my wife a quilt display board using 2-inch 4 x 8 foot polystyrene insulation board and while I was doing so, I thought that these boards would make great backgrounds and/or reflectors for folks who have the space to store and use them. I guess that I am not the only person to have this idea...
https://www.youtube.com/watch?v=U1S4wjXM6_U
The insulation boards that I used came from a Lowe's Home Improvement Store but, Home Depot and just about any place selling construction materials should have them.
The boards that I used are aluminum on one side and white (with a printed plastic material) on the other side. This plastic is a moisture barrier when using the boards as insulation in buildings and can be carefully peeled off to reveal a flat white surface. This gives you a double sided reflector...
The boards can be painted with flat paint of various colors for use as backgrounds and can be cut in half to make a more easily handled smaller background or reflector. You can also cut these in a circle to use as a reflector that will provide round catchlights.
The boards can be fastened to any light stand with clamps or the full size boards can be used with cheap shelving L brackets as feet to make a free standing unit.
As I said, you need a large space to use and store these boards but, if you have the room, they are a neat way to get reflectors and backgrounds on the cheap...
I didn't use Gaffer's Tape to bind the edges and make hinges for the foamboard, instead I used Gorilla Tape to fabricate my wife's quilt display board. Gaffer's Tape is great when you want a tape that you can remove without leaving any residue but, for permanent use Gorilla Tape is more secure, comes in several colors - including white, black and silver and at about $15 USD a roll for the 3-inch tape (actually 2.88 inches), is considerably less expensive than the Gaffer's Tape.
Here is an idea from an Australian company which actually sells commercially made V flats constructed of insulation board.
https://www.youtube.com/watch?v=ErcEMpon9Kc
Viewing this video, I should think that anyone with a bit of DIY skill could replicate these V-flats that they sell. They could be kept and used in a smaller space that the full size 4 x 8 foot board flats.
There are lots of other U-Tube videos about foamboard projects. This one talks about the colors Sue Bryce paints the boards for background use...
https://www.youtube.com/watch?v=rkezV6lI3qE&t=645s