Just to make that clear: my visualization ability is at 3 - 4.5 and this has no negative effect on my ability to create astral constructs or cast spells. What matters is if you can accurately define the function of each part of the creation, and represent that function correctly in your mind. For that you only need schematics on an abstract wireframe level.

Once created, you do not need to visualize the object, it already exists so you need only take in the image into your mind. As long as you understand it, you can use any level of abstraction, the meaning won't be lost.