correspondig project (not by me): https://github.com/DIYCharles/MouseJiggler
screws used:
https://www.screwsandmore.de/de/sortiment/schrauben-und-bolzen/schrauben-fuer-kunststoff/senkkopf-mit-torx/2-5/12668/25-stueck-pt-schrauben-senkkopf-a2-2-5x5-torx

switch i used has a 8x9mm base and a 5mm diameter stem, thats what i had laying around
modify .step for any switch of your choice
 

modify .step for different screws if needed

glue in arms, makes for a cleaner print