Rendered Sketch

Scale Prototype

Due to the lack of appropriate materials, the scale prototype does not include the metal rods which act as the seating plane.

This 1:5 scale model is made from a single cardboard net, cut and folded to produce this shape. This model has opened up the possibility of perhaps replicating the net and making it out of laser cut steel for the full sized prototype, instead of wood. The advantage of having a laser cut steel sheet may be in reducing the overall mass and also increasing the precision of hole alignment for the steel rods, by reducing the tolerances often attributed to human error during manufacturing with wood.

Further Concept Development

Considering the potential difficulty of actually being able to make a prototype of my previous preferred outcome from the ideation, I have developed my second favourite design, which I believe to be a more achievable design, considering the time constraints on this project and also my metal working know-how.

For this design I explored what possible shapes can be made within the 400mm^3 volume stool. I preferred to keep the walls of the design all perpendicular to the ground as to keep within the cube shape.
I also considered the ability of all of the sub-varieties of this stool to be stacked, as is helpful in a cafe, the most likely setting for such a stool.

I do not yet know what sizes of steel rods are available to me, so I have not yet decided on how many will be included in the final design.

Scale Prototype

The images above are of a scale model of my preferred design outcome. The scale of the model is 1:5 and is made from construction paper. Despite the material the structure is strong and can balance weight quite well, though I believe it may help to add supports behind the hanging columns to strengthen it in the axis running perpendicular to the curved seating plane. The final 1:1 scale prototype will likely have to be made from sheet steel and due to the small radius in the curve lines, will most likely require some cutting to aid bending.

I worked on various shapes and sizes for this particular stool until I was happy with how it was proportioned. The dimensions of the single sheet of construction paper I used to make this are 380mm x 80mm. The radius of the curved surface is 110mm and the length and width of the columns are 50mm by 20mm.

Lightweight furniture ideation and concept generation

Material Experimentation: Cardboard

To better demonstrate how lightweight materials can support a disproportionately large mass, I created two structures out of cardboard, using curved bend lines to create curved surfaces. This enabled the cardboard structures to support hundreds of times its own mass. The design in the top photo was the heaviest of the two, using multiple pieces cardboard. This design was the most stable, however it could not handle as much weight as the design in the second photo, this is because the surfaces supporting the mass during testing were not curved enough; after minor changes to the design (increasing the crown in the surfaces) the structure was able to support more weight. The design in the second photo was able to support the most weight, whilst still being the lightest, having only been made from a single piece of cardboard. The one problem this design did make very apparent was that the mass was not being distributed in such a way that did not cause buckling and twisting.

From this I learned that reinforcement of materials is not always the best way to strengthen a structure. It has become clear that clever design, through smart material choices and adjusting curvature can drastically improve results, especially when the mass of a piece of furniture is of great concern, second only to the safety of the person using the product.

Lightweight Material Research

Material Research: This post will contain the average densities of various forms of common materials, possible processes for manufacturing furniture, some of their properties relevant to their functional application as a component of a piece of furniture and their aesthetic properties as well.


Plastics

Common Forms	Sheets	Tubes/Rods	Mesh
Avg. Density (gcm-3)	0.800-1.500
Manufacturing Processing for furniture	Vacuum forming , line bending, cutting, bolting.	Bending	Line bending, cutting
Properties	High tensile strength, flexible, reflective, generally quite light weight. Form can be manipulated to strengthen structures.
Aesthetics	All can be glossy or matt, which reflects light in various ways. Many colours are available

Wood

Common Forms	Solid Timber	Laminated Veneer	Plywood
Avg. Density (gcm-3)	.600-1.200	0.500-0.800	.500-.900
Manufacturing processing  for furniture	May be cut, carved	May be bent, glued, ironed, twisted	May be bent, cut
Properties	Strong, rigid.	Flexible, brittle	Strong, somewhat flexible
Aesthetics	All may be painted, lacquered, veneered, or left natural

Steel

Common Forms	Sheet	Tube	Perforated Sheet
Density (gcm-3)	7.750-8.050
Manufacturing Processing for furniture	Sheets can be rolled, cut, bent to increase structural rigidity. Steel must be welded or bolted to connect parts.	Tubes can be curved, cut and welded.	Perforated sheets can be rolled, cut, bent to increase structural rigidity. Steel must be welded or bolted to connect parts.
Properties	Malleability, shaping can increase structural integrity	High strength, durability	Malleability, shaping can increase structural integrity, perforation maintains considerable strength and reduces weight of sheet
Aesthetics	Plain metallic surface, can be painted, or decorated with cutting out parts of the surface.	Surface can reflect light, can be painted. Industrialized look.	Has uniform pattern, may be painted, industrial look.

Paper

Common Forms	Paper Mache	Molded Pulp	Layered & glued
Avg. Density (gcm-3)	0.400-1.500 (depending on other constituents)
Manufacturing Processes for furniture	Gluing, cutting	Pulping, casting, compression, cutting	Gluing, cutting
Properties	Somewhat flexible, low tensile strength, lightweight, may need reinforcement
Aesthetics	Can be painted, not reflective (excluding paper mache)

Fabrics

Typically fabrics are not used as structural components in , due to their inability to maintain structural integrity under compressive forces, with the exception of woven fiberglass sheets and hemp fiber paneling. Instead the fabrics are used to make the seating, as they are generally good at distributing load evenly and have high tensile strengths whilst being able to stretch and bend. Examples of fabrics include: Leather, suede, wool, silk, cotton, hemp, fiberglass, spandex, nylon, acrylic and polyester. Depending on thickness, these materials have a varied density range.

Strings, ropes, hoses & wires

Strings, ropes, hoses and wires are all specifically designed to withstand tension and fail to maintain shape under compression, much like fabrics. Wires however tend to be much stronger under compression, given the shape has appropriately been manipulated to allow for compression to be withstood. Generally all of these materials are used for the seating in furniture and exhibit the highest tensile strength when woven together.