I was using 'Mendel Feed Spool' for a while.

http://www.thingiverse.com/derivative:8495

However, it was inconvenient when carrying by car.

I built 'Folding Spool Holder'.
However, since width is wide, this is somewhat regrettable...

A required thing:
-FoldingSopplHolder.stl x4
-Soolcap.stl x2 (following link)
-Bolt 5/16 x5
-Washer x14
-Nut x16
-Rubber cap(for foot)
-Bolt cutter(If required)

http://www.thingiverse.com/thing:5605

How to assemble:
1:Print these.
2:Assemble these.
3:Go out by car :D