Rashi: They are kinds of instruments.

Radak: Sipos are jugs. Perhaps they are what Chazal called Kiton (Sukah 28b). Yonason translates Kulaya, which is like Kulsa, i.e. Targum Onkelos of "v'Chadah [Al Shichmah]" - Bereishis 24:15]. Mezamros are instruments with which one sings.

Rashi: They are [buckets] to receive blood [of Korbanos].

Rashi: They are [spoons] to hold Levonah (frankincense).

Rashi: They are [pans] to take ashes from the Mizbe'ach, and to take coals from the outer Mizbe'ach to the inner Mizbe'ach to burn the Ketores.

Rashi: They are keys to open the lock. ¹

Targum Yonasan: Muglesaya. Radak - they are the hinge-pins of the doors ² . They were of gold, but the doors themselves were of wood covered with gold (6:31-35).