This is a simple adjustable & portable spool holder that uses 3d printed parts + a dowel.

The STL files are designed for an 8mm or 5/16" dowel. Print two base parts, and four rollers at 50% fill or greater. Make sure your rollers are not lumpy - if they are, use a file or sandpaper to get rid of the bumps.

Cut two legths of dowel equal to the width of your widest spool plus another 35-40mm or so to account for the dowel holder & roller brim. Insert the two dowels into one base part, slide the rollers on brim side facing out (so the roller brim is on the outside of the spool) and then put the other base on. If the plastic is smooth enough, the spool will rotate freely but the rollers may not turn. You may also have to tape/fasten the holder down to keep it from walking.

The width can be adjusted just by sliding the base parts closer or farther apart on the dowels.

The OpenSCAD files are included but note that if you adjust for use with a larger dowel, you may have to hand-modify the material-saving holes & top cut-out (or you can just delete them, per the comments in the file).

(Updated 10/23: Based on having a spool walk off the rollers, I increased the default brim radius on the rollers to 15mm. I have found I need to fasten the spool holder down because it's so light. I'm currently using binder clips at the edge of the table, but tape should work, too.)