I started with this layout with one arm and a track, but two arms are necessary to input suppress on the last pivot. This builds the first product so that 1 spare quicksilver is left over for input suppression, then the steady-state products are wasteless. Here are some ascii trees of the promotion recipes for the lone silver:

First product 4Q, 4L:
L   L  L  L
|   |  \ /
T   T   T
 \   \ /
  I   I
   \ /
    C
    |
    S

Steady state 5Q, 4L:
L   L   L   L
|    \   \ /
T     T   T
|      \ /
I       I
 \     /
  C   C
   \ /
    S

Hopefully the 26k instructions don't lag as much on your computer as they do on mine. I will make it loop later with waste-chaining if I have time.