Data Validation. Multiple Dependant Lists Required

Hello all.

On this spreadsheet, I have a couple of dropdown lists that I want to be dependant. I've included the dependancy descriptions in the file.

I've tried doing research on dependant lists but I can't wrap my head around the solutions that worked, or figure out how to expand on them to make them work for my problem. The main reason why I want it done this way is that if a value is not "present" on the table, then it has to be a "custom solution". In the end the only sheet a user will see is the Input sheet (with the resulting outputs).

ASTMFlanges.xlsx

Thank you very much.