A few quick shortcuts in Builder allow you to download and upload content from one content entry to another.
Download an entire page
In the editor above your page content, right click and you’ll have the option to Download content as JSON. Once you download the content from that page you can navigate over to a page in another project, right click, and select Upload .builder.json file.
Download a block on your page
In the Layers tab, right click on the parent layer you want to “copy” you can search for download selection as json. On your next page, drag a box component onto the page, right click the layer and select upload selection as json.
Upload your entire page content
Navigate to the content entry that you want to upload the page you just downloaded. From the Layers tab in the side panel, select Upload.builder.json file, select the file you just downloaded, and the page content will appear in the visual editor.
Upload your content block
Navigate to the content entry that you want to upload the content block you just downloaded. From the Insert tab in the side panel, drag in a Box. This will act as a container for your content. Right-click on the box, type “upload” and select Upload JSON into selection and your content block will appear in the visual editor
For content that you want to save and reuse on multiple pages within the same space, using a template or symbol would be a better option.