I reckon someone got sub-600 sum, but that someone ain't me.

My 1st solve was a 12:1 input every 8, costing only 190G but taking 600 cycles. My 2nd solve improved it to input every 4, coming in at 665 sum with a single use quicksilver disposal arm. 

This is my 3rd solve, getting rid of the single use arm at the cost of forcing 4P, with the copper arm stealing an iron once every 23 inputs to fix the quicksilver excess. 

Input every 4 seems like a natural sum convergence point, as you need many inputs per output. Disposing lead and tin follows from there, else you need >1 purification station. 

There's probably a way to get rid of the 5 wait cycles per loop to save 15 cycles, but I am not programming out this whole dang thing again.
