I have some broken panels on a Honda Scooter.  I have a hot melt wire repair tool that can repair and strengthen cracks by melting in wire clips from the reverse side of the panel but I have some pieces of plastic missing in some small areas. I was wondering if I could blank off from the back of the panel and use the actual hole as a mold and pour resin straight into the repair or do I need to make a pattern from clay and then a silicone mould and pour into that?  I thought I would shape the damage with a file and give the edges an angle and perhaps hot melt the repair in with my wire clip tool.
Any thoughts?