The Plumber's Choice 3/4 in. Plug End Cap Pipe Fitting Push to Connect PEX Copper CPVC Brass (5-Pack) 345UPSE - The Home Depot
Streamline 3/4-in Copper Rolled-Stop Coupling (25-Pack) in the Copper Pipe & Fittings department at Lowes.com
10Pcs) EZ-FLUID Plumbing 3/4" Solder Copper Pipe End Cap LF,Pressure Copper Cap Plug Fitting with Sweat Solder Connection for Residential,Commercial - Amazon.com
77717 - Viega 77717 - 3/4" ProPress Copper Cap
Everbilt 3/4 in. Copper Tube Cap C617 - The Home Depot
3/4" Copper Cap - Procuru.com - Plumbing, Electric & Lighting Wholesale