Are all weedeaters designed to be used for line that comes on spools? I used to have a TORO commercial weedeater that used just a single piece of line at a time and am having a hard time finding a new one like that. Do any single-line weedeaters still exist or are they history?
Not sure about a single piece of line, twit, but this site offers a replacement cutting head for string trimmers.
Mine has one line & I buy new line & put it on it myself. I don’t buy a spool. Those two line ones are too complicated. to spool
handy, what brand of weed eater do you have, btw? (Thanks, donkeyoatey.)
Still didn’t find one that comes with a single line twit, but www.jackssmallengines.com/KwikLoader.cfm+toro+weedeater+single+line&hl=en]this is closer:
Thank you very much, donkeyoatey. That part with the dual line was basically what I was looking for. 
Reminder WeedEater is a brand name of string cutters. It is not a generic term.
So is aspirin. Take one.
My straight shaft Echo has a single 25-ft line. Echos are about the best ones out there. I have had mine for about 9 years with no problems. The current models are still quite similar. Somewhat more expensive than the popular brands, but reliable and functional.
My John Deere 2-line string trimmer is no more difficult to load with line than a 1-line trimmer would be.
An advantage of 2-line trimmers: The head is more balanced so there is less vibration as it spins. Don’t know about you, but vibration make my fingers hurt after a while.
Trimmer line which is triangular in cross-section works better than any other type.
twit, I odn’t remember because I only use it once or twice a year…Its a very small one. I dont like to
use them professionally because they cut wood fences & let them rot. IF you need parts, ebay.com
probably has some cheap.
Loading a 2 string trimmer isn’t really brain surgery, folks.
load up one side, unwind it, make a mark on your garage wall to note its length, duplicate it, load them both up carefully.
Next time they’ll run out together.