My first design had a single bonder, and looked like it would be 82 but I didn't program it to completion.

Then I placed two bonders, trying to tuck things into the left 3 gaps, and got an 81.

Better layout got that idea to an 80 and I started secondary optimizing.

On the final night, I noticed the trick, and made a layout with 11 bonders. 
 Convinced myself it was possible to get 78, then iterated layouts and actually completed a 77, and went to sleep wondering how I would reduce the number of bonders.

The answer was packing things denser than the actual polymer, to allow the final segment to be built further to the right.  So this gets away with only 9 bonders.

I would have guessed 79 was the limit before finding the trick.  Now I think it's 74.