In our Dev Ghar ( देवघर ) there a Copper Plate with carving with circles and triangle in perfect desgin with center point in between and some Lotus Flower like shapes on circles.
I had curosity in my mind to find why this Yantra is worshipped by my everyone and my Ajji daily do Jaap and Puja of this Yantra , It had no photo of any God or Goddess.
So I asked my Ajji ( Grandmother ) about it and she explained me in very simple method.
Ajji told me that its Swami Samarth Siddhi Yantra by chanting Mantra and doing puja the Yantra gets activated and Swami Samarth Guru gives Prachiti (Experience) around us in any form which bring Positive Energy around us and Divine Sheild of protection is formed.
My Ajji told me that Yantra was created by Sapta Rishi after long meditation they created a some sort of Rangoli like thing in which the Shakti of the lord was stored and on doing puja the shakti was activated , I was meant to be use as touch and praying in front of the Same God.
Ajji said that She was worshipping Swami Samarth Siddhi Yantra which she brought from Akkalkhot many years ago , She purchased it and took it to Swami Samarth Samadhi and touched it and now at home she used worship it daily as that yantra Prachiti of Swami Samarth.
My Ajji further explained that how we bring Ganpati Murti to home for 11 days then we do Pran Pratishta and Aarti and give Naivaidya eveyday same is with Yantra only difference is that we do not do visarjan we just keep it Devghar and worship it everyday.