@Aurix@lemmy.world That extension is more for freehand drawing. For pre-made shapes and diagrams, you can use the Draw .io extension instead:

Freehand drawing: https://joplinapp.org/plugins/plugin/io.github.personalizedrefrigerator.js-draw/

Draw .io: https://joplinapp.org/plugins/plugin/com.github.marc0l92.joplin-plugin-drawio/