@MRALO Welcome to Polycount. Consider checking out the forum information and introduction thread. The object has a lot of repetitive surface features so try breaking it down into mirrorable or tileable segments. Working on a small portion of the mesh and copying it to create the rest of the shapes tends to be more…
@sacboi : well, the double lines on the red model are simply fillets. IMHO this issue isn't so much the CAD execution, looking quite good here ; but rather the fact that the *design* itself features a so-called impossible transition from an angular piece (top view) to something close to a perfectly smooth surface (blade in…