This is a replacement top 3" flat plate that is 3D printed But An Upgrade From The Original! It is designed replace the original, but with a significant improvement. The top plate part is made of firm plastic but the bottom attachment barrel is made of a slightly flexible material!
As you can see, the firm but slightly flexible rubber has nothing inside the barrel so it will just push your top on and it will hold FIRMLY without having to align it with the stem!
It works great and I hope you'll try it if you need one.  
Thank you! You won't be sorry!