Why not, you restore leather clothing and furniture so milliners should be willing to restore a decrepit old hat...but not as main bread and butter....more of a complimentary service if required! I will not redesign another designers goods or copy it! Restore, shrink, refit yeah!!!!
I completely agree with Edith.
For myself, I decide on each individual case. Depends on the person and exactly what they are asking, because I have done it as a complimentary service. I have gotten wonderful compliments. This helped to spread my reputation. I think it can be beneficial.
I consider it a learning experience. I cleaned, steamed and freshened up flowers, straw and replaced the broken wire in a fur felt hat while re-blocking the crown which was soft and dented, removed rhinestones and cleaned the straw then place the rhinestones back in place. I finished 4 hats without changing the original style while learning what can be done with battered hats other than throwing them away.