Hi
Im new at this, having made one uni-mould and one putty-mould before this.

i have a beaten plastic underside panel on my car that i was hoping to create a mould from.
As i have not been able to source a mint piece, this is what i have to work with.

Underside (facing away from the mould)





Side facing the mould



So i was thinking of taping and gluing it back together.
To cover the holes, where the plastic is gone i figured i could use some sort of backingplate, and fill it up with plasticine.

Any advice appreciated

To create edges I use glass putty (it's like normal putty, but it doesn't dry and you can use it several times); to polish it you could start with 1000 sandpaper and after 2000, I use wet sandpaper..and after for glossy some wax or polish will work well, matthieutje65 knows well, you can ask him