I have this question. I am wondering if say a friend of mine wants to make Medicine. to cure headache or just for training to be a real chemist. Think of a chemical like sumatriptan.

Is this legal?

Depends on your local jurisdiction. In .nl, there are lists of substances that are either only available through subscription by licenced medical authorities or not legal under any circumstances. The former is commonly considered to be "medicine", the latter "drugs". Sumatriptan is on the former list. (EDIT: this is wrong, it is not. Sumatriptan is not a psychotropic substance, so not on these lists. Sorry for the confusion)

If a substance is not on these lists, then you are still not free to do as you like, because there are also rules and regulations concerning hazardous substances. These apply to many of the ingredients for interesting experiments. With these regulations, small amounts of hazardous substances can be less problematic than larger amounts. The facilities for handling hazardous substances also weigh in. What you do in a lab in an industrial zone is regarded differently than what you do in your kitchen in a highrise appartment building.

^ This is true. I have read the same.

It does not mention the posession of controlled substance for legal purposes. . Edit; What I mean by that are intermediates, solvents etc.

Or the manufacturing of pharmaceuticals. I think this is probably licenced activity but I can not find anything to verify.

I'm wrong about sumatriptan; it is not on the opium list. Apparently there is no explicit medicine list in dutch laws.

Instead, there is a definition of "medicine":
http://wetten.overheid.nl/BWBR0...2015#HoofdstukI_Artikel1.

A body of experts is assigned to make judgements of substance:
http://wetten.overheid.nl/BWBR0...um_27-02-2015#Hoofdstuk2
and maintain a list of regulated medicine:
http://wetten.overheid.nl/BWBR0...015#Hoofdstuk5_Artikel60

As a tentative producer, you may want to study this (enjoy ):
http://wetten.overheid.nl/BWBR0...um_27-02-2015#Hoofdstuk3