Buying for a hobby I do not understand

They are deep into something you know nothing about.

They are serious about a hobby I know nothing about.

Tell me where buying is a bad idea because the choice is personal, technical, or depends on kit they already own. Then the safe zones: consumables, storage, comfort while doing it, reference material.

No specific brands or models as current, and no prices stated as fact. Say where you are unsure.

The hobby, and their level:

Finding a gift. Ideas built from what you know about the person: to a budget, made by hand, or needed tonight.