Here is a spooler I made for someone on #reprap. It works quite well and decided to share it.
Tap the holes with 8mm tap for 8mm bolts. (optional drill them through and use nuts)
use 4x 608 bearings. No spacing washer required.
Use rubber feet on the bottom.
Feed the filament through one of the holes in the front or back. The filament can also be fed out the holes in the A frame sides.(see photos)