Halbach array has superior magnetic force, but also has disadvantage of complex assembly process and high cost. It is important to consider the difficulty of design and manufacture before implementing a Halbach Array.
Large Halbach array rings are very difficult to assemble because of strong magnetic force. You can assemble them if you have a suitable workshop and appropriate tools and of course a lot of patience.
We have a customer, who needs a Halbach array used in a particle decelerator as a transverse focusing element. Considering very small size and hard to control the tolerance, our engineer suggest customer to use the normal direction. And finally, we made it successful and cost-effective.