I found the very nice Bambu AMS PTFE Buffer Block by K2_Kevin, but if you are using the spool roller mod then you can't use the buffer block he made. I created a new design, inspired by his, but made to fit the upside down spool holder with roller mod.

My design allows for the cable retaining clip to slip into it, has a rounded top edge that pushes the PTFE tube against the body of the printer, holds it lined up with the buffer, and clips at the top of the cable connector.

This design will also work if you are using the regular spool holder mounting method, without the roller mod.

Included are my STL file as well as my Bambu slicer 3MF file. It was printed at 0.2 Standard with auto tree supports, bed only, and takes 15 minutes. I printed this with black Bambu PLA Basic.