Project is an existing high school auditorium. Their back wall is cinder block. The stage is very shallow (adding rigging for a fabric cyc would kill precious inches), so I am suggesting they convert that wall into a permanent hard cyc, which can be painted (and re-painted) as they want—either a solid flat white for a cyc, or a scenic image to make a backdrop. I am thinking the most economical solution might be to propose an installation of vertical furring strips plus a layer of drywall, taped and skim-coated. Perhaps with a muslin cover sized (a.k.a. stretched and glued) to the drywall to dull and homogenize the surface. The initial installation is likely to be done by a construction contractor, so I'm hoping to find the best design that can be explained simply to achieve a seamless result from a non-theatrical installer. I welcome any opinions, better ideas and anecdotes on this topic. Many thanks.