I’d also suggest canopy glue for anything like lenses or window glazing. You can buy it at hobby shops. It’s designed for attaching canopies to model aircraft, hence the name.
If you are using any kind of modeling solvent cement (like Testors or Tenax liquid) or CA (super glue), it will attack and craze the clear plastic. I use Canopy Glue for gluing clear plastic. If you hobby shop does not stock it, Walthers has it http://www.walthers.com/exec/productinfo/547-56
I’ve tried CA glues, Testors model glue and Tamiya contact cement. Got so frustrated I was tempted to try Elmer’s. It starts out clear but then clouds over in all cases. I’ll have to try this canopy glue, assuming my hobby shop has it…
I use either MicroScale Krystal Kleer or Testors Clear Parts Glue. These have the added advantage that they can be used to fill small gaps and create small windows.