This spool stand uses 3/8" hardwood dowels with these printed brackets. You could really mix and match these to make other contraptions but I'll leave you to decide how you do it.

There is almost no bridging in this design and the layers are oriented in a way that provides good strength. I printed these with solid infill but you could easily get by with 20%, so long as the tubes are solid (use multiple perimeters).

Attribution - Creative Commons

spool, stand, filament, holder