I think what you mean are private items. Items that are private to you, and that you make yourself. They usually are a retexture of an item, and then for you only to use. You can also have a whole new item, AKA, a new item model+textures, but then you would've had to give us all objects pre-coded, and textured.
Unfortunately, private item/pet submissions are not open currently, and we do not have any current plans on opening them soon. With preset submissions opening in the future, we would like to worry about that more than private item submissions.
Private item/pet submissions were open in the past, but have been closed for a while now. They are different than Presets because they require a different type of coding.
Sorry for the confusion!