It is called a monstrance, also knownas an ostensorium
It is a place reserved for the adoration of Jesus Christ in the Eucharist. In such a chapel, the Eucharist is placed in a Monstrance so that it can be seen and worshipped.
The container that actually holds the eucharist is called a ciborium, it resembles the chalice except it has a lid usually topped with a cross, dove, or image of christ. The eucharist is distributed from the ciborium. The container in which the ciborium is reserved is called a tabernacle. The glass disc that contains a large host for adoration is called a Luna, and is kept in a round container called a capsula, the Luna is placed in a monstrance during benediction of the blessed sacrament. Both the capsula and the ciborium are covered with a veil within the tabernacle.
Your question is strangely phrased, so I'm not sure what you mean by "instrument". A Monstrance or Ostensorium is used to hold the Blessed Eucharist for Adoration, it is placed on the altar. During Mass, a corporal must be placed under the Blessed Sacrament, the Precious Blood is held in the chalice and the Host is held in on a paten or in a ciborium.
There are a several, namely the Mass, Benediction, and Adoration, that honor the Real Presence of Our Blessed Lord in the Eucharist.
pyx also pix (pĭks)n. # Ecclesiastical. ## A container in which wafers for the Eucharist are kept. ## A container in which the Eucharist is carried to the sick. # A chest in a mint in which specimen coins are placed to await assay. [Middle English pyxe, from Latin pyxis, box, from Greek puxis.]Taken from The American Heritage Dictionaries. (answers.com)
It is called a Pyx
The host kept in the tabernacle after Mass is the consecrated Eucharist, which Catholics believe is the body of Christ. This practice emphasizes the reverence for the sacrament and allows for the Eucharist to be available for adoration and for distribution to the sick or those unable to attend Mass. The tabernacle itself is typically a highly ornate and secure container, symbolizing the sacredness of the presence of Christ.
The eucharist is normally held in a church building although it can be held anywhere.
Roman Catholic AnswerPerpetual Eucharist Adoration is 24/7 exposition of the Blessed Sacrament with at least one adorer always present before Our Blessed Lord in the Sacrament of the Altar.
The tabernacle in the Catholic Church is a sacred container where the consecrated Eucharist, believed to be the body and blood of Jesus Christ, is kept. It is a focal point of worship and reverence for Catholics, symbolizing the presence of Christ among them. The tabernacle is used in religious practices such as adoration, where believers pray and meditate in the presence of the Eucharist, and in the distribution of communion during Mass.
The Sacrament is kept in a Ciborium. For adoration, the Holy Eucharist is displayed in a monstrance.
solids...