This Merkaba visualisation can be done in Savasana. The Merkaba energy field balances and revives the activities between the two sides of our brain and strengthens our sensitivities and mental abilities. Merkaba is also a powerful healing and protection tool and assists us in our spiritual growth. Within this energy field you are connected to a higher truth. From the Chakras we have branched energetic lines (meridians) that reach every cell deep into our body.  We have a Prana field that surrounds our body as a result of the meridians and Prana flow. Then there is the field of the aura. The auric field is an egg-shaped energy field that surrounds our body and changes colour according to our thoughts, feelings and emotions. After the auric field we have hundreds of electromagnetic fields, which have precise geometrical shapes. Each one of them is made up of three identical fields with the same size and shape. This Prana field is shaped as a tetrahedron, a three dimensional Star of David. This is your Merkaba. For a visual, you may want to look up 'Merkaba tetrahedron' in Google images.