All you need are some beads, nylon ( thick-ish ) and tubing ( spray bottle- ie kitchen floor cleaner )
The three pictured used coloured sea fishing beads, with a clear tubing collar, and 175lb nylon!
The one on the left had 60lb nylon.
I would'nt go below 60lb for strength reasons, catching it on a branch etc could pull and snap the nylon.
The centre holder has a small bead on the end of the nylon, is then heated, and flattened ( with a wet finger! ) and pulled inside the "blue" tube, two beads are then super glued on the ends. blue tube is a biro outer case.
To form the upper loop just cut a piece of tubing, fold nylon back into tube and apply super glue into tube, allow to dry, when dry test loop for strength.
The holders pictured will hold approx. 6-7 spools, however, you probably only need about four