I know this has never happened to you, but I think I may have over-engineered... :P The feed system in particular.

Instead of modifying the material to fit the machine, or modifying the machine to fit the material, let's meet half way. A thin enough ribbon should be feedable into a stock hot end. And if there is no forming necessary, only one extruder motor should be required. Makes everything easy, right? Well....

The pressure used to squeeze the molten plastic out the hot end is supplied by the still solid material being driven into the extruder assembly. If the material cross-section is square or rectangular and in a round hole, how will this affect the extrusion process? My guess is that we will get some squeeze-by going back up the extruder pipeline, cooling off and plugging up the works.

What can we do to minimize this effect? Change the shape of the pipeline. Using an extruder like this:

...we can deform a PTFE tube inside to match the approximate dimensions of our feed material.

One extruder motor (with a gear or hobbed gear) pushing through that custom extruder tube I mentioned in my first log I think.

The interface between this extruder, the rest of the printer and the hot end may require some thought...