Use a head pin to add a simple loop to each of the crystal beads. (See Jewelry Basics 101.)
Add one crystal bead dangle to the last link of one precut chain. Add 5 more crystal dangles to the chain at random intervals, but don't add any to the first link of chain. Repeat with other precut lengths and crystal beads.
String the first link of one of the embellished chain dangles on either side of the nylon tassel on the jump ring, and then attach to the shank of the button. Repeat with other button.
Add second jump ring to button shank and attach earwire. Verify that the button is facing right side up. Repeat.
If necessary, trim or tighten any stray threads from the tassels, and (optional) add a tiny dab of superglue to the tassel wrap.
2 each #61-460-40-02 40mm Nylon Cord Tassel - Black
2 each #59-100-27-AS TierraCast Antiqued Silver Plated Britannia Pewter Scary Skull Button