Learn Finnish: Käsityöläinen on ylpeä tästä käsin tehdystä korusta. - The artisan is proud of this handmade piece of jewelry.

This matches the rule for complex participial attributes. In Finnish, any adverbs or dependents modifying a participle must be placed immediately before that participle. Here, the adverbial käsin (by hand) must come directly before the participle tehdystä (made), which in turn premodifies the noun korusta (jewelry).

Why are tästä, tehdystä, and korusta all in the elative case ending in -stä or -sta?

The adjective ylpeä (proud) always requires the thing you are proud of to be in the elative case. Because the main noun korusta is in the elative case, the words describing it (the pronoun tästä and the participle tehdystä) must also take the exact same case to agree with it.

Why doesn't käsin take the elative ending like the other words in that phrase?

käsin acts as an adverbial here, meaning it modifies the action of making (tehdystä), not the jewelry itself. It is formed using the instructive case of käsi (hand) to mean by hand. Because it is acting as an adverb, it is locked in this form and does not agree with the case of the noun.

How does the verb tehdä become tehdystä?