Guilford of Maine has a ton of fairly exotic fabrics that come in 64 inch widths.

I just wrap the fabric around sharp corners on the wood and use my electric stapler to staple it on the back of the frame. Then I butt them up tightly against each other. as tightly as possible... On the back of the frames and on the wall that they attach to, I use this super wide (3 inch) industrial velcro and using a rubber mallet, very carefully tap the panels into place... (On yachts, most all of the walls and ceilings are panels that attach and can be removed in this manner.

Takes a little practice, but it's sort of like in the olden days, when some of us were in the speaker building business and we made our own cloth grille covers our our speaker monstrosities.

I'll do a little digging around on Google today for more specific info.

There is a company called SANPTEX that (might be national) that will do the walls for you, professionally. They do a lot of corporate board rooms, and locally I've used them for higher-budget theaters or listening rooms.