Dynamic Dropdown Menus for Google Sheet

I need a sheet updated so that three columns are dropdown menus. Level 1) Hardware Category Level 2) Item The Level 2 Dropdown will be filtered based on the selection in the Level 1 dropdown. Content for these dropdowns will be based on data in a secondary sheet. i.e. Monitor | Desktop | Laptop | Printer P2219H | Opti 7080 | Latitude 7410 | HL-L6300DW P2419H | Opti 7070 | Latitude 7480 | MFC-L5900DW The document already exists, it only needs the formulas added for these two columns.