Cupchain connector was designed specifically to accommodate 4mm cupchain. Simply add a dab of glue to secure, place cupchain in connector, push down then bend 2 prongs over with pliers. Connector can also fit other types of cube beads smaller than 4mm in size.
Chain Terminator>Gunmetal>GreysFindings and Components>Terminators>Chain TerminatorGunmetalGreyshttp://www.firemountaingems.com/itemdetails/h20a6176fnH20A6176FNConnector, gunmetal-finished brass, 4.5x4.5mm, fits 4mm cupchain. Sold per pkg of 50.//image2.fmgstatic.com/images/pa6176fnb.jpg5.845.84As Low As $0.05 per connector