[TR] VIN tag rivets

[aribert at c3net.net]

You and I are not allowed to buy the special rivets used to attach VIN
tags.  The form is exclusive for automakers (and maybe DMVs to attach
state issued VINs for assembled vehicles - never been down that road). 
Without looking at a VIN tag, I seem to remember that the edges of the
rivets had subtle flats around the perimeter.  I seem to remember gently
using a fine file to duplicate.  I do not remember if the official VIN
rivets also used a hex mandrel or not - I remember seeing rivets that had
such.