197. The material "out of which" something is made or constructed is
expressed by use of the preposition "el". As in English, an adjective
may be used instead of the prepositional phrase unless a verb or
participle lays stress upon the fact of construction:
La tablo estas farita el ligno, the table is made out of wood.
La tablo estas ligna (el ligno), the table is wooden (of wood).
La infanoj konstruis domon el negxo,
the children built a house of (out of) snow.
Oni faras supon el asparago, they make soup out of asparagus.