Forget the Thingiverse spool holders. Or any printed ones, IMO. I have a dreamer and tried most designs, from the ones with rollers, bearings, hangers, you name it. What I've settled on is shown in the photos - some plastic plumbing pipe.
All the joints are glues (I used hotmelt but whatever works) except for one of the horizontal ones, which is how you load a spool. To fix that in place I put a 3mm hole right through and then stick half a cotton bud in there. No particular reason for a bud, just that the shaft fits the hole and the cotton bud stops it falling out.
Of course, this is an external spool. I found that 1kg spools just came in too many shapes and sizes to fit inside decently, plus they restrict your attempts to prise things off the bed.