Room acoustical treatments

Wish to go minimal without nailing or adhering panels behind speakers.  Does someone make a 4-5 foot diffuser I can free stand or slightly lean against the wall behind each speaker?  Thanks
What you are looking for is commonly referred to as a GOBO I have a pair from GIK and they are cheap and work well
GIK Acoustics is awesome. Ask them for help.
+1 Gik, communication is key here

celtic66 - I'm a fan of Tim Perry's (Arqen) lean diffusor.  Its a DIY project that would cost you a couple sheets of MDF.