Hi Henning

Thanks for posting in the Lucidchart Community! You can share custom shapes within your team. To learn how to do so please take a look at this instructional video. Unfortunately there is not a way to share Custom Shape Libraries directly from Lucidchart with users outside of your team. If you've uploaded the shapes into Lucidchart using PNG files or files of another format you can send those files to other users. The users with those files can then upload them into their own Lucidchart accounts to allow them access to these shapes. I hope this helps!

Let me know if you have any questions.