The following criteria were the aspects we considering when choosing a design:

• Must be reliable and durable.
• Must be cheap, light, and strong.
• Must be easy to use by people of all ages.
• Must be completed before the engineering design fair.
• Must fit into our given budget.
• Must require little energy to use.
• Must look professional and aesthetically pleasing.

We then developed several possible ideas, which we evaluated against our design criteria using a design matrix: