Two words, very inexpensive and easy to come by:
- also known as foil/mylar “RESCUE BLANKETS”
~You heard me right - they are thin, highly reflective mylar. I got a pack of ten from AMAZON for around six or seven bucks. They measure 52" by 84" or about 1.32 by 2.13 meters.
They are water and weather proof - somewhat strong but very thin.
Since I am using in inner room that is an unused bathroom (they are in the tub/shower enclosure, in fact) these make an excellent liner material, plenty tall enough to go up the walls.
They can be put up with tape and thumb tacks…
If you’ve been looking for an easy to get and easy to work with material that doesn’t raise questions - this is just the thing