Yantras
Yantra may be used to represent the astronomical position of the planets over a given date and time. It is considered auspicious in Hindu mythology.
These yantras are made up on various objects i.e. Paper, Precious stones, Metal Plates and alloys. It is believed that constantly concentrating pray of God or Devi /Devta helps us to build fortunes, as planets or nominated Devi /Devta have their peculiar gravity which governs basic emotions and karma.
These yantras are often made of Rock Crystal, Copper plate, brass plate, Gold, Silver or Asht metal in shape and composed in pattern of commonly in dots,lines, square, triangle, cirle, floral, representing in different ways the subtle energies.or many other designs with complex and detailed symbols, mantra on a particular date and time according to procedures defined in the vedas. Every Yantra is delimited from the exterior by a line or a group of lines forming its perimeter.

These marginal lines have the function to maintain, contain and prevent the loss of the magical forces represented by the core structure of the yantra, usually the central dot. They also have the function to increase its magical and subtle force.
A yantra is a very complex spiritual instrument in the taantrik practice . It can calm and focus the activities of the mind, and by its positive energy it has a benefic impact on the health and psychic well being of a person.
Yantra function as revelatory conduits of cosmic truths. Yantra, or instrument are work on spiritual technology. Certain yantra are held to embody the energetic signatures For example, the Universe , consciousness , ishta-devata.

Though often rendered in two dimensions through art, yantra are conceived and conceptualised by practitioners as multi-dimensional sacred architecture and in this quality are identical with their correlate the mandala .
Meditation and trance induction that generates the yantra of the subtle body in the complementary modes of the utpatti-krama and sampanna-krama are invested in the various lineages of tantric transmission as exterior and interior sacred architecture that potentiate the accretion and manifestation of siddhi .

Mostly The Yantras are made or Siddha by Panditji or Priest according to their religions. But I think do your work yourself. To maintain power of yantra you must be pray or pooja daily yourself by chanting Mantra according to yantra for five minutes to reap benefits , otherwise the yantra will not work properly.

There are negative energies around us . These negative energy obstacles in our way of achieving greater success, affluence, Harmony and Peace. Many times we find that life is out of our control.
We find ourselves in a position of Extreme stress , lack of peace and harmony , high degree of anxiety , friction in relationship with others , Bad investments , faltering business , stagnation in life and profession , decreasing financial prospects , insecure feeling , repeated failures . Though we involve our best efforts , hard work , intelligence and good intentions.

Shri Yantra

Shri Yantra : This Yantra is precious to get money and wealth. Shri yantra is the source of super energy to get wealth and it has a magnetic power to attract money . Shri yantra is a divine energy source to pick up cosmic rays emitted in constructive vibrations and get positive energy then spread in its , surrounding area. The Instrument of Wealth or the Shree Yantra brings us materialistic and spiritual wealth. Shree Yantra give us unexplained spiritual power to fulfill our all wishes and change our life. Shree Yantra is complete solution to all the problems in our life. Which Person is using Shree(shri) Yantra achieves peace and harmony . Shree Yantra helps in breaking all the Obstacles in our life. Shree yantra means shree means Money and yantra means Instrument then we can say Money instrument or Shree yantra. In the Shree yantra we worship of Goddess Laxmi, (the Eternal Goddess of Wealth & Prosperity). Shree Yantra is the source of supreme energy and energy is nothing but another form of element in the shape of waves and rays. Shree Yantra is highly sensitive and has magnificent magnetic powers. Shree yantra is said to be a divine store-house of energy which pick up particular cosmic ray wave emitted by the Goddess laxmi ji and other universal objects and transform them into constructive vibrations. These are then transmitted to the surroundings where the Shree Yantra is placed, thus destroying all destructive forces or bad enery within the area or vicinity. Shree Yantra is source of supreme hidden powers which can be noticed within a short period. Our All desires are fulfilled by keeping a yantra and chanting the Mantra of the Goddess Laxmi and the worshipper is never lacking in money & material comforts – his house & treasury are always full, and he & his family never face shortage of resources. Shree Yantra may be placed in cash box, almirah, purse or in temple of your house after worship (pran pratishta). Shree yantra brings success and wealth through regular Pooja and mantra chanting.
Beej Mantra of Shree yantra is as follows : “Aum aim hreem hreem kleem shreem”.

Instructions For Yantra Pranaprathistha :

1.  After having a bath in the morning or at night you must be sit with your favorite
posture padmasan or Sukhasan in pure mind and soul.
2.  Yantra should be placed on a wooden board in front of your isht Dev picture or
place slightly slanting backword, facing a little upward.
3.  Look into the center of the Yantra, trying to blink as rarely as possible and observe
the whole Yantra at once and chanting the Mantra according to Yantra at least 15 to
30 minutes or 108 times.
4.  Within eleven days of Yantra meditation you will be able to tap into the same yantric
energy.
5.  Maintain a state of aspiration and intense longing for experiencing the beatific
energies of the consciousness.
6.  The priest or Pandit must be give complete attention to siddh/ energize yantra or
pranaprathistha . Yantras should always be used on the level above ground. A
Yantra without bija Mantras is not beneficial.

A Yantra must be engraved with the bija and other Mantras and surrounded with the matrikas, or letters of the Sanskrit alphabet. Before use, or installed with life, a rite called Pranapratishta .
There are many other Yantras which have their own individual shapes. The meaning of yantra’s wordsa are the Devirahasya. Shiva is the Seer, Trishtubh the Metre, Parashakti the Devata, Shrim the Bija, Hrim the Shakti and Klim the Peg. After doing hand and limb nyasa, one should meditate on the throne of the given Devi as being in one’s heart. The Mantra differs for each material:

After using the appropriate Mantra, the Yantra should be placed on a pedestal (pitha),infront of your Isht Dev related God/Goddedd of yantra and bathed with the Panch Amrit ( Milk, Ghee, curd, Sugar, Honey) and Gangajal water of yantra then Sandalwood paste or Chandan or Kumkum must be offered to the yantra then Scent and flower, unbroken rice, fruits betel nuts betel leaves are also must be offered to the yantra.
Then Incense sticks and diyas ghee lamp must be lit worship the appropriate Devi/Dev in the usual form within the Yantra.
This all should be done at night.
Then the appropriate root Mantra or Beej Mantra should be recited at least 108 times. This is considered to be a highly potent way of concentrating magical power.
The time to do this is during an auspicious astrological period. The Yantra should be drawn using the eight Kaula perfumes. Outside the Yantra the root Mantra should be written.

On the outside of this the armour (kavacha) and 1000 names should be written. The Devi should be invoked into the Yantra in due form. All good substances are to be used. The Yantra is then entwined with gold and silver thread, and placed into a metal holder and may be worn on the person.

Before any Yantra is a suitable object for puja, it must be given life (pranapratishta). The following, from Nityotsava, describes the process. This, process, incidentally, also holds true for initiation of a candidate into Shri Vidya. The rite installs the 35 tattvas into the Yantra.
It also gives the Yantra the full set of senses and the Antahkarana, or subtle body. It is said that engraving a Shri Yantra on gold is said to hold good for life, on silver for seven years.The process also imbues the Yantra with the matrika, the letters of the Sanskrit alphabet which are the goddess as sound.