PVC Pipeworks 3/4-in Schedule 40 PVC Cap in White (10-Pack) in the PVC Pipe & Fittings department at Lowes.com
3/4 inch PVC Plug, For Plumbing Pipe
Amazon.com: 20PACK 3/4 Inch Female PVC Pipe End Cap 3/4 Inch Female Threaded Plug Adapter, SCH 40 PVC Pipe threaded Cap Fitting 3/4" PVC Pipe Female Plug Socket for Plumbing Water Line,
Charlotte Pipe 3/4 in. x 1/2 in. PVC Schedule 40 MPT x S Reducer Male Adapter PVC 02110 0600HD - The Home Depot
Supply Giant 5-34PPPL Plastic PEX Poly Alloy Plug End Cap Barb Pipe Fitting 3/4 Inch Pack of 5 - Walmart.com