Just hang and roll!
This skate-bearing roller setup will easily hold your 1kg spools. Throw these small gadgets in a box until you need them. To use these rollers, simply remove the spool from the "shelf" and place 2 lefts and 2 rights on the 1x2 shelf edging. Replace the spool. Your spool is ready to roll, literally!
These simple rollers only require 1/8" clearance to the next spool. These drop onto any 1x2 (1x-whatever) with room to spare for easy drop-in-place and lift-out. The edge-flange is limited to one side in order for a full spool to roll unimpeded.
These quick prints take about 1/2 hour each. Print a pair of left side parts and mirror for a pair of right side parts. Print 4-each bearing keeper rings. And go "borrow" a few of your kid's skateboard bearings. The bearings fit loosely all in keeping with a stress-free design. Even the keeper is just snaps on.
For the child-deprived... skateboard bearings are 8mm ID, 22mm OD, and 7mm thick. As I am one of those childless beings, I had to dig deep for a pair of bearings. Then I got to thinking, only the front spool managers really should have bearing rollers. So I made another set called "TheBackNine". This includes some dummy bearings if you have nothing else. These do add some style as well as including both left and right all in one print. Mix and match as you will.