You have have the hotend linked to a mobile coupler that is having a cutting blade, the coupler is moved by a lead screw and a stepper motor. The cutting blade is mandatory because the filament end will be larger and you cannot put it back safely in the hotend.
You have the filament driving stage, that is a collection of 5 hobbed gears for the 5 driven filaments.
And you have the most interesting part which is the filament selector implemented with a "revolver" holding 5 bearings where each bearing is set at a specific position to engage only one filament. Probably there is a free wheel position, once the filament has been grabbed by the extruder of the hotend.
I do not yet have all the details regarding the filament detection and other tricks.
It seems to be a sound approach, that can be also implemented by DIY.
