heart chain 
 a lobster clasp and extension chain
 3mm rings
 6mm setting connectors and 4mm pendant

Super simple assembly:

Start by measuring your wrist, then subtract the value of the setting connector. Divide the value by 2 to get the length of the chains.

Cut the 2 pieces of chain. If your measurement does not perfectly match the positioning of the hearts, reduce the length of one heart; the extension chain will complete the bracelet size.

Then connect the chains on each side of the setting connector with 3mm rings.

To finish, cut a piece of extension chain about 3cm long, then connect it with a 3mm ring to one end of the bracelet. To nicely finish the bracelet, place a small setting at the end of the extension chain. 

On the other side, place the clasp with a 3mm ring.

And there you go! Beautiful creation!