Some people believe in making thoughtforms, that is (if I understand correctly)a bit of their own energy so to speak set into motion for a specified purpose. The beliefs of these ranges from a simple thoughtform -- basically an imaginary bundle of energy used for a task such as magical energy storage before a demanding work -- to beings with some level of autonomy, and more from there.
Everyone I have ever seen post about them has said even the basic ones can be demanding, and require a lot of concentration. The more involved, the more it takes, and the longer just the planning stage can be. They recommend journals, and some who believe in the use of an energy bank (a physical object used to store excess energy) say that it is very useful to the task. Some thought forms can supposedly take months or years to construct.
Still some others say that a basic thought form is not quite so difficult to create or dissolve, but still must be very specifically created for its purpose. They say that adding autonomy is when things get complicated.
I have not gone very deep into the study of these for myself, thought I find the concept fascinating on many levels.