Now... we know what drove Lawrence Marvick insane in TOS.
It wasn't designing the Enterprise's warp drive that drove him nuts, -- least of all some chick he just met in in the transporter room or a ball of light she was bringing along, -- he'd just gotten done making a replica of the Enterprise and realized he glued his wallet inside the engineering hull!
Bad joke, I know....
Still, stories about surgeons leaving instruments and medical cloth inside patients' guts are true.
I also know personally that one family found a beercan inside their car door.
It isn't beyond the realm of possibility that at least one modeler left a tool or something else more valuable inside a model that was just finished!