In most Catholic churches the tabernacle is constructed to resemble a house. This reflects the basic symbolism that it "houses" Jesus, truly present under the apperances of bread.
However, in some places a tradition was established of constructing tabernacles within statues of the Virgin Mary.
Father Stefano Manelli in his book, Jesus Our Eucharistic Love, briefly explains this tradition.
More recently a unique monstrance was constructed for St. Stanislaus Kostka Parish in Chicago that possessed similar imagery.
It was called "Our Lady of the Sign - Ark of Mercy," and found its inspiration in the Ark of the Covenant found in the Bible.
This idea of Mary being the new "ark" or "tabernacle" of God is a long tradition.
For example, the ancient Akathist hymn of the 6th century reads, "Hail! tabernacle of God and the Word. Hail! holy beyond all holy ones. Hail! ark gilded by the Holy Ghost. Hail! unfailing treasure-house of life."
Furthermore, Pope Benedict XVI reiterated this imagery in a homily on the feast of the Assumption.
While this tradition of constructing a tabernacle within a statue of the Virgin Mary is not widespread, it is an honorable custom that recognizes the beauty of Mary's role in salvation, and her image as the first "tabernacle" that housed the body and blood of Jesus Christ.
