The mind is connected to the element of air and is a very practical place to release sigils from. Sigils can be activated from the mind by focusing and envisioning the sigil in your mindscape for a period of time then visualize it being released outward. This can be useful so that you will be able to use sigils even when you do not have tools to make it physically. When a sigil is charged and activated within the mindscape it can be sent out from the mind in order to manifest without the use of external processes. You are then able to target people by being in proximity to them or by focusing on them as well in your mind.
This would be like focusing on a sigil for good luck in your head, so you can invoke good luck to you. A practitioner could also focus upon a sigil, and somebody else in the immediate vicinity in order to connect them to their will, and cast it upon them, so that they will be affected by their desire.