I am reading between the lines, but I am going to guess that the shrinkwrap
was the Faceted Solid variety. For parts, there are two types, Surface
Subset, and the Faceted Solid. Assemblies add one more type, the Merged
Solid Type.
Based on the comment, 'but they said the polygons were too dense', I am
betting the resulting faceted model was tessellated, and therefore not
useable.
Shrinkwrap is still a likely candidate for providing a solution. I'd suggest
creating a merged solid model, and then exporting that as needed. (File >
Save a Copy. > Wavefront (.obj) ) etc.
My $0.02 for the day.
-tsl