1965 Dodge Dart Charger

While polishing some mouldings tonight I found the kick-panels. They are in great shape but needs to be reproduces. BUT, look at the plastic moulding that goes on the front towards the door opening.It is sewn in place from the backside.

Question is, how did the make the stiches without going out on the front side through the plastic moulding???????

I even found the factory insulation taht goes behind the kick-panels. They are in such a great shape that I will reuse them is they are.