since I'm in china it's easy to source these materials as long as you have the patience & google translate via a VPN then your ready to go
just got those reflective cloth (Anti Light Reflecting), first was the thick light gray one which is used for EWD on clothing which was delivered folded & the other was a little dark gray thinner material which was delivered rolled. The first was much heavier & thicker than the 2nd cloth. Yes the viewing angle is really small as can seen from the sample shots, some shots where taken at an angle around 30deg (estimate) while other shots where taken Head on. It seems the thick reflective cloth is more brighter than the other but not very much. got both in taobao here in china. oh how I wish I could put a Frame on these! these where done around 5PM with windows behind me.
can you imagine shining a 1200ANSI Lumens on these, my eyes
Messy experiment below using Xgimi CC 350ANSI
dirty white wall & two type of ALR screen
on axis
offaxis
reference, plain wall