I suggest that you try to find some plastic bins that are almost see-through and fit the space. That would be two for each of the lower shelves. You could pull out the bins to see what is inside and even label the outside. Or you could cut your plywood to fit the space and support it on the built-in shelves with bricks or purchased legs. The problem with this is that things in the back would be even more hidden than they are now. Then for the upper left you might be able to find a set of shelves that would fit. For the top right, I would put big soft things that you can grab and that won't hurt you when they hit you on the head! This might be extra bedding, towels, out-of-season clothes. For children's clothing I like to fold the whole outfit together, so that one doesn't have to hunt for the "matching" part. I think that your cosmetics could be in a small box that fits on top of other bins or clothing on shelves. Good luck. This will take some experimenting, but something will emerge.

is it a curved staircase? What is the highest point of the staircase? maybe you can do something like this image:

Hello Durga, I hope you are doing well. Open wardrobes are a great option, however, you should also know that they can be a bit difficult to maintain, especially if you have pets or kids. One thing you can do without affecting the spaciousness of the room is install pretty curtains over the wardrobe, like so .. With the layout you have shown, you can also add a mini dressing as well + curtains. So the upmost shelf will have plants/ any other decor you want, whereas the back part can be used for storage. And when you aren't getting ready, you can just pull the curtains below the plants. As shown below (Click the link for pictures) So the first column would be hanger rods, possibly two rows, you can store other items/ clothing in the middle rack and the last column would be a Mirror - A full length or a medium sized one with table and some storage as shown below - However, do add a lighting option above the mirror for better illumnation, possible off-white rather than white, since it closely mimics daylight. A mirror will also make your room look bigger. The following is another option that you can easily implement with your current wardrobe layout You can also use some wallpaper or beautiful wrapping papers (Fabindia has some very beautiful ones) to give a lovely backdrop to your wardrobe! Hope this helps!

You can't increase the depth of cupboard by just adding plywood doors. You have to apply wood to sides of the cupboard also. Suppose you have a corner cupboard, then either on left or on right side you have to add a wooden plank vertically. In this case the final cupboard will be a few inches out from the wall. It will look a bit awkward.