Here is a github repo containing over 600 "little electronic art projects":
https://github.com/tardate/LittleArduinoProjectsThere is also an accompanying web site:
https://leap.tardate.com/A quick perusal of the repo and web site suggest that the author has actually built all of these projects and the pages contain his/her notes in a very well-presented format.
The github repo is very large - it will be a multi-gigabyte download. There is an online tool at
https://downgit.github.io which allows you to download just a single directory of a repo so you can extract single projects.