My first solve of the puzzle was a full throughput 170g, which turned out to be a rather easy to get cost, but didn't feel optimal.
Very quickly I figured out a layout for 160g, but didn't get the programming quite right. Only the next day I managed to put everything together and ended up with this solution.

Sadly, arm 3 cannot output all the metals, as it only has 3 grab points. As I couldn't get purification done with 2 normal arms (as both arms would have to have access to the lead input and output to not disturb the 1:1 ratio required for the purification, this meant I needed to figure out how arm 3 can hand one output over to the lead handling multiarm. To get the timing right was the hardest part.

In the end, the metals produce in the order Cu-Cu-Sn-Au-Ag-Sn-Au-Fe-Ag-Fe (4426526353), with arm 1 setting aside 2 Fe while arm 2 outputs the two Cu.

I can't rule out 150g, but didn't really try to investigate further after finding my solve.