Check out books and catalogues for inspiration. The first cupboard I planned to make was a Chinese style black and gold one. In this instructable the same methods are used for every type of object you plan to make. I will show step by step techniques of how I made a craft cupboard to store my knicks knacks.
Check out my other instructables for details on how to make your own door hinges -https://www.instructables.com/id/How-to-Make-a-Cardboard-Hand-Puppet-Stage/new tips and tricks for cardboard furniture:https://www.instructables.com/id/Cardboard-Triangle-Corner-Cupboard/
So now you've figured out you basic construction. You will be surprised at the strength of your cardboard structure. This cupboard below holds up to 80kg of folders.
After 3 months its still standing!
Look for clean cardboard thrown away in electronic superstores. Large complete pieces are ideal - the size of a refrigerator or plasma tv. I clean any visible dust with hospital grade 90% alcohol. Let dry.
You will need to work out the measurements for thicknesses for each layer ON PAPER.
6-10cm is ideal space between each LAYER.
Thicker ply of cardboard is definitely going to make aa stronger cupboard or chair or table.
In one structure I used 2-ply cardboard other times 3-ply.
1 ply is all that's necessary for the shelf layers (more on this later)
When cutting the shapes of the cardboard use a simple craft knife. Slice 3-4 times over the line you've drawn without using pressure. You'll be surprised how effortless it is compared to working with WOOD.
Sharpen your knife often. I used the side of brick and its brillant.
Accuracy in MILLIMETRES is essential, or your structure may collapse. (Seriously.) NOTE THE DIRECTION
of your cardboard. If you cut on the vertical GRAIN
each piece will be stronger than if you cut a horizontal grain.