In the sentence "they were extremely well made", is the "made" a noun or participle? Could the "made" be a noun? Thank you very much!
It's a participle. 'Well' is an adverb modifying 'made'. Consider also:
The were extremely well painted/decorated.
You couldn't replace the verb form with a noun, but you could with an adjective if you removed 'well' also.
They were extremely flat/old.