Plastic Grill Housing Repair

The trick to using zip ties as filler is puddeling enough original plastic and mixing it really well with the Zip plastic, when I shape it I use a body dolly, get the plastic just the right temp(juuuuuust enough where it will compress) and mush it flat with the dolly.
You can just push hot staples in the plastic to hold a bad crack together enough to fill it.
PLastic welding isn't common knowledge and a lost art.