Recently, a few composers in Reykjavík have been developing alternative clarinet barrels along with Halldór Úlfarsson experimental instrument designer.
Stefán Ólafur Ólafsson had this idea and approached Halldór and Þráinn Hjálmarsson with this idea and since there have been various versions of 3d printed clarinet barrels with strange shapes, sounds and forms.
I along with several other Icelandic composers have written pieces utilizing this and I have quite a few already that use the model CRU 3.2.1.
This barrel has traveled into the hands of performers like Ingólfur Vilhjálmsson, Kristine Tjøgersen, Kyusang Jeong, Grímur Helgason, Sigurjón Daðason and members of the BBC Scottish Symphony.
Þráinn Hjálmarsson has some additional info on his website.