The transparent case is no longer produced. You can only try to find a used one on the inofficial marketplace here. Note that the transparent case (and the other “regular cases”) was prone to breaking easily and its two elements (the flexible black rim and the stiffer back part) tended to become uncoupled from each other.
Thanks for the tip, will check it out.
I don’t have a 3D printer but I hear some stores start offering that kind of service… Worth a try I suppose.
Although the result might look less nice than the original ones.