Step 1) Pick a domed bead cap with wide base. It also will need to be a bit deep to cover the gathered chain.
Step 2) The chain you choose should compliment the size of the cap.
Step 3) Choose a stronger wire to work with for strength and design. Copper Soft Beading Wire 20 Gauge (Six Feet) Reference: W02
Step 4) Get a baseline for how long you want the tassel to be and make a guide. Copy until you get the thickness of tassel that will fill the cap.
Step 5) String the chain then twist before putting wire through top of cap hole.
Step 6) You can add stones, beads, connectors or create a loop with the sturdy wire. If your chain is uneven, just remove links as needed to even out the tassel.