If someone pulls off P4 1P (which would be min rate) that would be slick, but I don't think it's happening due to how difficult it is to achieve the necessary lateral motion in time.

I pretty much exclusively worked backwards on this one, as you have to.  I did find that you could avoid all the problems of horizontal wrong-bonding by building an expanded form of the polymer that resembles tall-very-dark-thread-but-explosive, then doing some cool debond-rebond reshaping that may be a flavor of syrup.  In this form, the only issues to contend with are calcifier placement and lateral movement.  But, when I found solutions for these, they turned out to provide a cleaner and faster solution that didn't use the very-dark-thread intermediary at all.  To turn my solution here into that intermediary, move the rightmost bonder one tile to the left and get rid of the arm on the far right of the polymer.

In fact, feel free to remove the rightmost arm entirely when showing this on stream.  nonlooping is annoying but optimal, it's 6 cycles