To create a tile displaying a specific Pinterest pin, open the pin on https://www.pinterest.com.
Click the ellipsis button and then click the "Embed" menu entry.
Copy the code and then paste it into a "Text" tile's "Content" field

Pinterest Pin: A suitable tile size is "2x3". Content:<a data-pin-do="embedPin" href="https://www.pinterest.com/pin/99360735500167749/"></a> <script async defer src="//assets.pinterest.com/js/pinit.js"></script>