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.