The great thing about standards is that there are so many to choose from. Filament spools certainly do not deviate far from this sarcastic saying. So what are we 3D Printer folks to do? Here are a couple completely different DIY options:
[Mark] made a spool holder that can accept 2 different width spools. This design uses skate bearings to support the spool on two points at each end. There are 3 sets of bearing blocks to accommodate the 2 different width spools. When either size spool is installed, one of the bearing block sets goes unused.