I had some extra PVC pipe and fittings so I threw together this super basic spool holder mount.  I used 3/4'' PVC pipe, with a T connector and two endcaps to stop the filament from sliding off. The two top pieces of PVC were cut to about 160mm, and the center piece was cut to about 200mm, but any size will work. The pipe then just friction-fits into the “pvc spool holder v4.stl”, which mounts to the table with 4 #12 ¾ inch screws. Its also pretty sturdy, so you're fine to just throw a spool on just one side.