First off this is how I did this might not be the best way probably not the only way and by no means the supported way of doing this use this at your own Risk

this project is to feed filament from a btt smart sensor out side the machien to the tool head inside the machine this can be done with or with out filament switch at the tool head I have macros for both here

I used a couple of Klipper addons to do this succesfully the Annex engineering belay extruder sync sensor https://github.com/Annex-Engineering/Belay this one is required and Klipper Dynamicmacros
https://dynamicmacros.3dcoded.xyz/ this is only needed if you want to have it feed to the switch on the top of the tool

in my setup I am using a sherpa Mini with filament switch and ECAS fitting found here https://www.printables.com/model/999921-sherpa-mini-with-ecas-and-integrated-filament-sens but any extruder with a fitting to secure the ptfe tube will work I ahve used cnc mini sherpas and regular mini sherpas with a mount for a m10 fitting to hold the ptfe

you are going to need to source about 3-5 input pins and a stepper driver pre tool you want to add this too 2 inputs for the the btt smart sensor this is optional you could a simple filament switch or a button to trigger the loading 1 input for the Belay sensor and 1 optional button for unloading (I used a 6mm tactile button) I used a spare older 8 bit board I had with 5 stepper drivers also a option input for a filament sensor on your tool board

you will need a extruder with a fitting to secure the ptfe for each tool aswell I used BMG/bmgclones and I did test a sherpa mini with a fitting but found the bmg was able to push the filament faster down the ptfe but you could deffinatly use a sherpa mini or any of the dirivtitaves I will inclue my test mount

there is a fair bit of configuring I will include some of my files as examples

I have also documented this build on the stealth changer discord https://discordapp.com/channels/1226846451028725821/1401147182639481004 if you have any questions this is probably the best place to ask

My macro's require you to have a purge bucket and brush as well as a working Clean nozzle macro

after adding the relivant setting for Belay and dynamic macros to your printer cfg you will need to add LOAD_ANY_TOOL T=0 S=30 D=1360 T being the tool number S is the speed in mm/s and D is the max distance

[filament_switch_sensor filament_sensor_tool0] switch_pin: ^MMB:PC15 pause_on_runout: FALSE runout_gcode: M118 Runout sensor tool0 reports: Runout SET_GCODE_VARIABLE MACRO=tool0 VARIABLE=filament_consumed VALUE=1 insert_gcode: M118 Runout sensor tool0 reports: Filament Detected SET_GCODE_VARIABLE MACRO=tool0 VARIABLE=filament_consumed VALUE=0 LOAD_ANY_TOOL T=0 S=30 D=1360