Finishing the part made from ABS Plastic
The easiest and simple way in case 0f 100% perfection is part of your Criteria
A Sample how to make a glass surface finish as same as your fuselage body

Assemble the part using liquid Plastic glue from Hobby kit like ; i.e. Tamiya, Revell or Humbrol. Please be advise this glue will allow you minutes for fine adjustment before it sets. However once it sets, it is
permanently welded (not only just glued) and structurally become
very strong. as this is an ABS Plastic
permanently welded (not only just glued) and structurally become
very strong. as this is an ABS Plastic
Filler can spray

Use Can spray filler and spray it generously layer by layer. After several layer you can
see in the picture (left) what it looks like. make sure it is completely dry.
see in the picture (left) what it looks like. make sure it is completely dry.
After Fine sanding

Time to start sanding, use only fine grit of wet or dry sand paper (600 grit above) as
this will be the final sanding. Do not use medium or rough grit sand paper, this will
leave a deep scratches marks and will force you to start spraying again.
this will be the final sanding. Do not use medium or rough grit sand paper, this will
leave a deep scratches marks and will force you to start spraying again.
Ready for finishing paint job

Final preparation can use a Grey primer can spray paint before finishing paint job.