formual help with totalizing and multiple drop down columns

I'm trying to make a formula where it will auto sum from columns but I'm using drop down to 1) populate the columns and 2) to select the items.  The drop downs would vary based on the process I'm mapping out so I'm trying to make a spread sheet that I can adapt for each instance.  For example I 1 test might use product 1,2 5 only  while another might use product 1 3 times, product 2 1 time and product 4 5 times.  I have tried v and x look up with out any success either.

Any and all assistance would be greatly appreciated.  I am using windows 10 and using home and office 2016 for Excel.

Thank you in advance for any help with this!