Mine is not 1000' but I use a reel from a kite.
Stickweldr
I use a cheapo $18.00 flycasting flyreel, ( It will not hold a thousand feet however.) for my camber and straightness stringline. For my 32 ounce plumb bobs, I use an H-frame. For my 8 ounce plumb bobs, I use a gammon reel. I also have a Bazooka Bob, for column plumbness, which has no external string. For long stringline work, as with progressive assembly, I use a 35 pound, 12 " roll of 0.045 stainless steel electrode. I use 50 pound pull magnets to hold the string line taught, and wedge lock tensioners or Bessey clamps for the wire line used for progressive assembly camber measurements.
Joe Kane
I use a chalk line reel (un chalked) for the plumb bob we use the most. Obviously not good for 1000' though.
Griff
I use a chalk line reel too, but I use fishing line, it works for me but dont get it to close to a hot weld.
I just got done doing some fence and I bought a string line of 1100 feet. Rolling that thing is us a job init self. My plumb bob is a whole lot shorter and that i wrap on a small piece of tubing. just looking for a quicker method. Chalk line holder sounds good.
I use a chalk line holder with 90LB test parachute string, its very thin string and strong. you can get at least 2 times more string than regular chalk line in the holder.
Use a old mig wire spool. Make it into a large flyrod reel, that will hold a 1000ft maby 4000ft.lol
Try one of those orange estention cord holders with the handle in the middle and the crank up handle.
Try up grading to a laser plumb bob. About 100 bucks, but not affected by wind and never needs rewinding. The real drawback is it doesn't work well outside on sunny days, but inside it is awesome. Wish I had one 20 years ago.....jeez.