Project Source 10-Pack 1-1/4-in L x 1/4-in dia Standard Drywall Anchor (Screws Included) in the Anchors department at Lowes.com
10" End Cap Round Duct Fitting, 26 ga.: Amazon.com: Tools & Home Improvement
Plastic Caps - Round Caps - Vinyl End Caps - Rubber Cap
Aluminum Spacers (10 Pack) - OpenBuilds Part Store
Prescott Plastics 1" Inch (25.4 mm) Round Plastic Hole Plugs, Inserts, Black End Caps for Metal Tubing, Hardware Plugs, Fences, Glide Protection from Chair Legs and Furniture - Pack of 10 - - Amazon.com