Hi Cedric,
Rhino won’t automatically know which way you want your parts orientated of course, you need to put that logic in somewhere. You can use the Orient command in Rhino to speed up this process if you’re not already doing it. For more than one element, it does sound like using Grasshopper to automate your manual layout process might be the way to go. I just wrote a post on using the ‘Orient’ component for that purpose that you might find helpful:
Best wishes,
John.
PS: Adding an image with a question like this would help us understand your problem more clearly.