This freestanding filament spool holder should fit most spools no wider than 87mm. Tested with MakerGeeks, FilamentOutlet, 3D Solutech, Hatchbox, and Sainsmart.
The holder is based on the 140mm height Filament Duck Spool Holder: http://www.thingiverse.com/thing:187987.... which is a remix of http://www.thingiverse.com/thing:143424. I love the clean styling of the original Filament Duck Spool Holder ... but it would not hold most of my spools.
The axle/cylinder is from this freestanding filament spool holder: http://www.thingiverse.com/thing:634588. I found that holder itself to be too flimsy to hold together even with lots of super glue (at least for me) but the axle from it works well here.
Spool holder printed upright and axle printed vertically. No supports needed.
The FastCap Traction Dots 56-piece fit very well in the indents on the bottom of the spool holder. They are 9/16 inche diameter. I got them off Amazon but I am sure they can be picked up cheaper elsewhere.