This is a really cool idea. I think the limitations are that you can only make filament rolls that are small enough to fit on your bed, and the precision with which the colours match the intended part depends on how much oozes out when you're priming the nozzle.
I noticed that some of the parts shown in the video appear to have a wipe tower next to them. Presumably this is because the G-code was generated with Cura or similar, but given that the filament is one continuous piece with colour changes in exactly the right places, it seems like you could skip the wipe tower? Or maybe it's better to keep the wipe tower because it reduces the precision required in priming the nozzle?
> can only make filament rolls that are small enough to fit on your bed
I suppose you could print filament of arbitrary length by doing batches that get pieced together.
Here's my best idea so far how to do it:
(1) Instead of a spiral, print in a double spiral. Meaning a spiral that starts on the outside, goes to the middle, makes a u-turn, and then goes out to the edge again. (For the u-turn, I assume filament has some minimum turn radius and as long as you stay above that, it's workable to straighten it out.)
(2) Pause printing, put a clamp over one end of the printed filament, yank the rest off the bed and wind it on a reel.
(3) Resume printing, and repeat as many times as necessary.
I think the tower is still needed because when the filament changes you will have a blend, as old melted filament inside the head will combine with the new filament, it takes a bit of time/material to clear.
I noticed that some of the parts shown in the video appear to have a wipe tower next to them. Presumably this is because the G-code was generated with Cura or similar, but given that the filament is one continuous piece with colour changes in exactly the right places, it seems like you could skip the wipe tower? Or maybe it's better to keep the wipe tower because it reduces the precision required in priming the nozzle?