Add a custom picklist with variables

[Lukasvd123]

So I am trying to make it so when you are making a new record of a custom module of mine that one of the picklist drop-downs will have the names of all the records that have been inserted in the "Projects" module. Now I am not certain in how I should do this I have seen possibilities in CRON and automations with workflows but its not very clear how to have them working and how to debug these custom scripts and how or if its even possible to have those dropdowns with custom values according to a script. (for example I have array of names that is assigned each 15 minutes or on modification of a project which updates the picklist) and then once someone uses the dropdown they can choose from all the possible projects that are in existance to tie it to.