This is my entry for Joel Telling's spool holder design contest.  It prints flat in 3 sections and snaps together.  It hangs from the board by two hooks and has a hinged catch on the bottom to reduce movement when loading the spool.  Spools are loaded in the same manner as the toilet paper holder that has been making the rounds on the Facebook groups.  Simply lift the spool up so that it pushes the two hinged-support bars until they drop into the center of the spool.  To remove the spool, simply pull it straight up.