It was clay and fell off the slider before it made it here. Added material under the swingarm and at the front of it.
There was also a styrofoam piece in case the puttty fell off.
I think if you fill in the whole gap It would make it too heavy.
Just needs reinforcement long the bottom front and next to the tab next to the rear bolt.
Racer726 new material most likely be more flexible and stronger then the stock hard plastic. Let’s let him work his magic.