In what activity can I give some advice:

My experience is based on the jobs I did in the past 25 years and the technical parts I sold.

Foundry: I worked for 13 years in an aluminium foundry as a commercial and we produced parts in sand casting, die casting and high pressure die casting. Our factory had his own machining, heat treatment and testing.

Moreover I was an internal auditor for the ISO system and calculated offers and prices and decided on the subcontractors to work with.

Machining: For 6 years I sold turned and machined parts.

Gears: In the same 6 yaers I was involved in selling & calculating gears from 1 to modul 12 including all the inhouse random activities like heat treatment and grinding.