I just built some shoji type sliding doors with a pvc shoji paper that was attached with double sided tape. The technique for getting a smooth surface with a flexible material is to start at one end and roll it on. This requires you to set the frame flat and to flex the sintra a bit so you only contact one edge and then slowly roll it down onto the frame. If you try to just place the frame on top of the pvc I'm pretty sure you'll end up with flexing across the screen. That's my experience in putting togetther a large number of panels. The slower I rolled it on, making sure I was getting a good bond with the double sided tape, the less waves I had on the finished product. Oh, yeah. I recommend the double sided tape because the bond is quick with no waiting for the glue to set. Set the tape and only peel the second side as you work the sintra down the frame.
Home Theater Man Cave: Onkyo 7.1 Klipsch LaScala Mains, Shortened LaScala Klone Center, Klipsch Academy Surrounds and Rears; Panasonic AE8000, Panasonic BDP 460, 117" DIY Screen.
Garage Man Cave: LaScala Industrial Splits; Second hand Denon Amp