A filament runout sensor is a lot cheaper than a pallette 3. I’m not sure how many scraps at the ends of spools you would have to use to pay for a pallette.
I am printing a bunch of boxes for drawer organizers as a “back burner” project. It is perfect for the ends of spools because a box with a little less height is still usable. I just let it run out.
Ryan, are you doing any kind of weight estimate to guess if you can fit a part in the remainder of a spool? I would guess you could get within 10g or so that way. You could measure a few empty spools, then measure a couple different sized parts (measuring the spool before and after, probably). Then measure low spools to decide which part will fit, and use up the most of the remaining filament and chuck the last bit.