The problem with center axis spool rollers is that the have TOO little friction, every unbalance in the filament spool will show. And the filament slipping of the spool has also happened to me. So I took on the design of a tube spool roller where the spool rides in between and the filament has lees chance of jumping off. Also the available designs here on Thingiverse are having the spool ride too high for my taste - it's a balance thing.

This spool roller is designed to take 1kg spools up to 78mm width.

EDIT
I did include a sleeve roller for the 608 bearings as an alternative - in case my tube rollers turn out bumpy. See the warning below.

WARNING
Designing stuff and assuming things is one side - actually seeing what the printed piece will do is another. And that's the problem with the rollers: every bump & imperfection will show during the rotation of the spool. Due to the retraction blobs of Simplify3D the rotation is very rough & bumpy, even after I sanded the heck out of it. Now i know why so many folks are using the 608 bearings directly instead of printing a sleeve tube. So try the rollers at your own risk because the roundness quality depends on your slicer settings and printer performance.
Even after rotary sanding my roller tubes had flat spots, the spool is rolling like on wooden wheels. You'd have to print them with 100% infill to make sure that they are 100% round. And even with 0.1618 layer height I got some bumps but this time from the layer start/stop points. Not a severe like the retraction blobs but still enough that the roller tube stops spinning. You'd also have to sand these spots down...