Upholstery and egg crate type foams will not be rigid, and may not be flame retardant. EPS and XPS construction insulation foam are lighter weight, more rigid, and could be covered with batting and fabric. They come in 4'x8' sheets, but can be cut with a utility knife into smaller sizes. They are available from a big box home improvement store like HD or Lowes. Not sure if they are flame retardant. Depending on how large a piece you are mounting, I would think they may be light enough in weight that they could be mounted to the wall with 3M removeable hangers of some sort.

Hi, I am from Assam, Guwahati. Yes it is warm humid place with lot of rains (like kerala). The bookcase is gradually drying. Fortunately last few days were very sunny and airy and my room has two big windows. Few mor details of my bookcase. It is 8 feet wide, 6 feet tall and 11 inch deep. It was attached with wall with 6 wall screw and has four pair of legs.I ask the carpenter to divide the bookcase into 3 part (32 inch each) and two door system for each part. Every part has 6 shelve from top to botom. There is no plywood or wood in back. I made it that way because the bookcase is attached in my room's inner wall I understand that the bookcase may have very little gap in between wall and wooden planks and i am ready for it. But I have no idea that beacuse of faulty mesurement, it became 1 inch gap between wall and sheve in the upper side. In lower side it is very minimum gap. I stop the carpenters to put the glass door. But now I see that they also make fault in making the doors. The doors are heavier that the shelf. The wooden planks are 1 inch thick while the door are 1.1/2 inch thick. I actually visit few hardwere shops here, but most have no ideas what to do and few says to apply wall putty to fill the gap. But my back wall is coloured (old wall, that why) and wall putty will not set on old wall and timber. I cannot remove it now from the wall otherwise the wall may destroyed. I really need a step by step guide now that what to do after the heves are dry, how to fil the gap and how to put the door without further damaging the shelf.

I feel partitions are not needed. You already have too much for the space. Adding a partition will shrink the space further. The simplistic solution, you do not wish to discard any furniture would be to paint all the walls in lighter pastles. And use some wall painting frames to highlight certain walls.

Go for hardwood plywood like birch or oak—they're durable and look classy. Ply with a smooth finish is perfect for furniture. Check the thickness; 3/4 inch is solid. Ensure it's free of knots and defects. Quality matters, so invest a bit more for long-lasting and stunning interior furnishings. Happy crafting!