Breakdown of Das Werkzeug wechselnd, versucht er, feine Konturen zu formen.
er
he
versuchen
to try
wechseln
to change
das Werkzeug
the tool
Questions & Answers about Das Werkzeug wechselnd, versucht er, feine Konturen zu formen.
How does the participle clause Das Werkzeug wechselnd function here?
Das Werkzeug wechselnd uses the present participle (Partizip I) to express a simultaneous action. It tells us what he is doing at the same time as the main verb. In everyday spoken German, this structure sounds very formal or literary. You would more commonly hear a subordinate clause like Während er das Werkzeug wechselt,... (While he changes the tool...).
Does the person changing the tool have to be the subject of the main clause?
Yes. A strict rule of free participle clauses in German is that the implied subject of the participle must exactly match the subject of the main clause. Here, er (he) is the one doing both actions: changing the tool and trying to shape the contours. If the subjects were different, you would have to use a normal conjunction like während or als instead.
Are the commas mandatory in this sentence?
Strictly speaking, both commas are optional under modern German spelling rules, but they are highly recommended. Placing a comma after wechselnd clearly separates the participle clause, and the comma after er neatly sets off the extended infinitive clause (feine Konturen zu formen). Leaving them out would make the sentence much harder to read at a glance.
Why use formen instead of bilden for 'to shape' here?