Got my posters done, ordered from Spoonflower on 4/23 and they shipped on 5/3. I went with the Performance Knit and they turned out great, nice colors.
I bought the 1X4 poplar from Menards - about $8.00 for 8'. Nice straight sanded wood, didn't do any prep - used them as is. Also used Nick's idea of little metal "L" brackets in each corner. Air-nailed them together - they went togethor quick and easy.
Used Roxul safe-n-sound batts. Its all I could find locally and I didnt want to pay shipping for the other products mentioned. They are 3" thick and pretty rigid, seem to work fine.
Thanks to Nick for prepping the pictures with a black border, that made it easy to get them centered. Just pulled the fabric around and stapled, pulled just enough to get the wrinkles out - not really streching
Opps, meant to add this to the DIY Custom-Printed Movie Poster Acoustic Panels - cheap!, not start a new thread, is there a way to move it?