I first built my reprap mendel a couple of years ago and quickly understood the need for a spool holder as I watched the unravelling filiment twist, tangle and break during my first large prints.
I looked for existing designs for spool holders, but they were either large, used additional vitimens, used a lot of plastic or were custom designed for a specific printer.
I wanted something fast, and simple so that I could leave my printer running without hand holding the filiment...
this is my solution...
[
repables.com]
by having the spindle horozontal and balanced on a central, low friction pivot I was able to print effortlessly from a 2.5KG spool.
give it a shot, leave comments, suggestions or improvements either here or on the site.