In Parshas Beha\’aloscha Hashem commands Moshe to create two silver trumpets to be blown when it was time to travel or when people needed to gather together by the Mishkan. They were also blown on festive days while various communal offerings were being brought.
We made silver trumpets to represent the ones created by Moshe.
בהעלויתך י:ב
Beha\’aloscha 10:2