Our lunchbox design:
Our lunchbox was designed with simplicity in mind. We wanted to create a lunchbox that was easy to bring around, both before storing food and after the food has been consumed. This meant that the box would be able to fold as much as possible, and there would be minimal exposure of its inner layers after folding (to minimise the need for immediate cleaning after consumption).
During our design process, numerous other factors also had to be taken into consideration, such as its watertightness (to ensure food can be securely stored), durability (especially with folding mechanisms involved) and size (both before and after folding), all while using only food-safe materials.
Eventually, we decided on the design as shown above. Our design is a simple two piece lunchbox, with the box and the lid above. The internal dimensions of the the box is 18 x 10 x 5cm, with a capacity of 900ml. After folding, the dimensions of the lunchbox will be about 10 x 11cm and about 3cm thick.
The Lid
The lid is made up of three parts: two sides and a piece of silicone connecting them. By using a flexible and stretchable piece of silicone to connect the two pieces, the lid is allowed to freely fold along the middle. At the same time, the connecting silicone allows the two halves of the lid to be connected in a seamless manner, ensuring the lid’s water tightness.
As can be seen from the image above, one half of the lid has a “U” shaped piece of plastic surrounding and extending below it. When folded, this plastic piece covers the gap between the two pieces, preventing any leftover food contents stuck to the lid from flowing out and dirtying wherever it is placed.
The Box
The box is made up of two main parts: the flexible silicone box and the hard polypropylene plates attached to the outside of it. While the silicone is flexible and folds easily, we had concerns with the usability of a sole silicone box. This is because it is too flexible and may not fold as we planned for it to (fold where it should not), or worse still, fold while the user is eating out of the box. Furthermore, it might not be able to handle the weight of the food.
Hence, hard polypropylene plates will be glued to the silicone box, as shown in red above. These plates are shaped depending on where the folds are designed to be, with additional grooves being moulded into the silicone to allow it to fold more easily and reduce any stress and strain at the folds.
As shown in the picture, the folds are between the red polypropylene plates. The shorter sides are first folded down towards the base, which will also cause the longer sides to fold down. The box can then be further folded again along the folds in the longer sides and base to half the flat surface area.
In addition, to prevent the box from folding when it is filled, a loop is installed at the short sides where a flat piece can be passed through to hold the box in a rigid manner as illustrated above.