In essence, a servitor and thought form are the same thing. I previously wrote of the creation of a friend that is placed in a charm in the white magick area which again is the same thing just using a different name and creating it in a different manner.
At the most fundamental level, all creations begin with the persons will. Regardless of all else, it is the will of the practitioner that will actually create the desired being whether it be a servitor, thought form or a friend in a charm.
Most beings work best when they are given well formatted direction at the beginning. This means, if you are going to only use your creation for inspiration, you would want to use things that bring to mind inspiration whether it be pictures and art, runes, or maybe even just thinking or writing the word inspiration on a piece of paper. If you have not given the form a definitive direction at the commencement, you could run into trouble. Think of your creation like a child. He or she will know nothing you don't tell her or him. You can also not ask a child to do something; you have yet to instruct the child to do.
I will also note: When using chaos magick, many practitioners absorb there creation later on while when using thought forms, the practitioner will often release the creation to be in the wild and those that create there friend in a charm generally keep it for quite a while. In using a charm the desire is usually to bring one confidence and calmness which could be used at any time through a person's life.