My partner and I have a client's house that we are hired for painting & design. All the walls in the 4200 sq. ft, 30 year old home is the old style 4 inch wide panelling with the indented grooves. The client is tired of looking at it, but there is no drywall behind it - just frost walls. We have to either paint over it (which it will just look like painted panel), or come up with a nicer/easier/cost-effective solution. Putting up drywall would be a great solution, but not in the budget and filling in all the grooves would be too time consuming.
Answer:
Thee may be a form of wallpapering that would work (remember the old grass type stuff?) but other than that, we're back to drywall.