H2D/H2C - Fix for broken extruder pneumatic connectors - avoid $25 replacement part!

Did the metal ring that grips the PTFE tube pop out of your H2D or H2C's extruder, and the tube is no longer secure? Use this fix to save $25 on replacing the extruder idlers, as Bambu does not provide the black pneumatic connectors for individual sale. Without it, an AMS will continually push filament through the tube, as it won't register enough resistance. Extra center hole accommodates a dedicated tube for the external spool slot, making it less of a pain to switch. -- For general use, print in PETG. If you print with a heated chamber, use ABS to counter heat deformation. Uses 2x ECA-S04 fittings that press-fit snugly into the top holes, but I recommend super gluing them anyway. The fittings come in 3 pieces - you DO NOT need the small rubber piece on the bottom. -- Alternative to adapter: I found the fittings to be nearly the same size, so I popped out the broken connector from the assembly and superglued in the ECA, then used the stock black plug instead of the ECA's blu