[rochellle]

  play the flexi while it was on top of a normal 
  vinyl single, or place a coin or two somewhere 
  near the centre of the disc—some later Soundsheet 
  pressings actually contained a circle marked out 
  for where the coin, or coins, should best be placed

Seems kind of obvious in retrospect, that the format could have been improved with an adapter to clip the discs into, but oh well.