Design Development
To develop your design, you need to look at your initial sketches and choose TWO DIFFERENT DESIGNS to develop.
The process is about making SMALL CHANGES to your designs and analysing the effect (good or bad)
You are going to use: -
Plasticine and card to model the pieces you want
TinkerCad to go through the design development process, so you need to take screen shots at each step so you have a record of the changes you make to your design work.
Record these changes on a Google Slide Presentation. There is an example here.