Repairing a cracked demonstrator

[Formulansx]

I'm curious if anyone knows how one would go about repairing a cracked body in a demonstrator without replacing it?? A little background on this, I picked up an Omas Vision demonstrator in blue but found the body had a crack in it near the piston filler knob. The seller took the pen back and refunded my cost with shipping. He's having it repaired professionally and I've expressed an interest in purchasing the pen once it's been repaired. I'm unclear if the body is being replaced or it's being repaired. How would one go about repairing a tinted blue clear tube without it being noticeable?? I have no idea!