Sure...! I use Cura normally.
After slicing I openend the gcode in a text editor and searched for G92 E0 because I know that the e value is ressetted when it gets to high.
In this case it is resetted after around E1600 E1700.
From that value I calculated the mm of filament. In this case the 'flavor' of gcode was 'Marlin' so the E value is mm length. (Flavor 'UltiGcode' -> volumetric extrusion amounts, flavor 'Marlin' or 'Reprap' -> lengths extrusion amounts).
Then manually count the 'find next' until you reach about 60 meters, in this case the length of the spools.
Then I placed a "M118 //action:pause" command to trigger the pause at octoprint.
Then repeat for the next change.
To do it in OctoPrint or Marlin would be fairly complicated because various slicers manage E values differently (i.e. absolute vs relative, resets at layer changes, etc.)
Yes and no. I think Octoprint already states something about filament (cannot check right now).
And yes, I think where to do it has different benefits.
In cura: perfect, then you just say the length of your spool
In Marlin/octoprint: Then you can also initiate it when you grapped a used spool and you see during the print you have only x meters left.
There is already a material change option on the lcd in marlin, that could be place to make an (advanced) option where you can choose after x meters (or after x height or after x layer)
Same could be for Octoprint, although I haven't seen any plugins (yet?!) where you can 'program' an action in the future.
(Another nice plugin would be: Do gcode x after layer/height y. For example when you started a print but then realised that the top part is more narrow or has tiny towers so you want to lower the speed or temp for that section. I should start a new topic for that. OR make this plugin 'request' more general so this fits in there as well......)
you can move the object below the print bed
Keep in mind that the bottom layers are solid then unles you set them on 0 with the initial bottom thickness setting...
cheers / joris