Using data binding and state, you can build a custom and reusable symbol with a dropdown to modify the content of a page. In this example we build a dropdown that allows a visitor to this site to choose a specific size and see a specific image that corresponds with that choice. Watch the video below for an exploration of how to accomplish this.
Here is an example Builder fiddle with the same content for you to play around with. If you are having difficulties with the fiddle or would like to create your own version, you can also create a new entry in your account, download the builder json file from the fiddle (right click on the preview and then click download content as json), and then go to your new content and right click on the preview, and select upload .builder.json file.