Reaching the AMS feed tube to disconnect it to switch to a single spool around the back of the printer is not easy. Most of the Y splitters available are in my opinion too long and stick out, so adding to the path the filament takes on each change.

My solution adds the minimum length and keeps the AMS path as straight as possible to avoid friction or blockage. It requires only one PC4-M10 Straight connector. The manual feed single spool tube is slightly curved, similar to the filament as it leaves the spool and adds very little friction.

I added a back plate which positions and holds the splitter at the correct angle to connect to the original PTFE tube connector. The back plate is designed to use two new longer fasteners not the original ones. I found two suitable screws in my workshop that were the correct thread, only needing cutting to the correct length. I am not sure what thread Bambu use, does anyone know?

I printed the splitter in PETG. Upright, with the output 4mm tube on the printer bed, using the 0.12 Fine setting, 2 layer raft and tree supports. This allows the thread for the PC4-M10 fitting and the hole for the PTFE single spool in feed tube to print as cleanly as possible. I will leave you to decide how long the spool in-feed PTFE tube needs to be, mine is approximately 50mm.