From VIS, some details behind the urns that will hold the votes for pope:
The function of the urns is described in Chapter V of the Constitution, which also speaks of a plate to be placed on top of the first urn. Every cardinal, in fact, must “place his ballot on the plate, with which he drops it into the receptacle beneath.” The second urn will be used only in the case of the presence in the Conclave of cardinals impeded by illness from leaving their rooms and the third urn will be used to gather the ballots after the scrutiny, before they are burned to produce the traditional smoke announcing to the faithful gathered in St. Peter’s Square either the non-election (black smoke) or the election (white smoke) of the new Pontiff.
The urns are the work of the Italian sculptor Cecco Bonanotte, already known for the new entrance doors of the Vatican Museums that were inaugurated on the occasion of the Jubilee Year 2000. They are made of silver and gilded bronze and their iconography is linked to two fundamental symbols: the first is that of the Good Shepherd and the second of charity. The symbols chosen by the artist for the three urns—a shepherd and his sheep along with more subtle birds, grapes, and ears of grain—are united in a simple and direct way to the meaning that the person of the Pope has in the Church: the shepherd, indeed the Good Shepherd who, in the name of Christ, has the duty of “confirming his brothers” (Luke 22:31) in the faith.
The symbolism of the Good Shepherd, however, also underlines the style of exercising this primacy, which is indissolubly linked to charity. This idea is clearly expressed in the Gospel of John (21:15-25) where “feeding” the flock is joined inseparably to loving care: “Simon of John, do you love me?…” Peter tells him: “Lord, you know everything, you know that I love you: “Feed my lambs.” The relationship of love between Jesus and Peter, and as a consequence between the Pope and the Church, is emphasized in the other symbols used to decorate the urns: the birds, grapes, and the ears of grain. Eucharistic bread and wine, which are Christ, accentuate the idea of charity underlined by the sharing of this very bread and the chalice.