Printed from flexible material for easier attachment to the buffer using a pneumatic fitting connector ( https://www.aliexpress.com/item/1005002680262764.html ). Print them from a flexible material with a hardness of D80-D95, after printing, cut off the support (see photos), insert the connector and into it a PTFE tube, which you push about 2-3 mm further. After placing it on the buffer, push the tube in as far as it will go.

EDIT 06.05.2024 - Version 2
Sometimes it happened that the rubber on the bottom of the pneumatic fitting connector came loose, so I added a breakpoint to the bottom of adapter.