Amazon.com: 72" Long Acrylic Rigid Square Tube (Clear) - 3/8" ID x 1/2" OD x 1/16" Wall (Pack of 2) : Industrial & Scientific
1/2" x 4' Heavy Wall Square Clear Plastic Tube | VisiPak
Amazon.com: Prescott Plastics 0.875 Inch Square Plastic Plug Insert, Black End Cap for Metal Tubing, Fence, Glide Insert for Pipe Post, Chairs and Furnitures (10 Pack) : Industrial & Scientific
3/4" OD x 0.060" Wall PVC Square Hollow Tube | U.S. Plastic Corp.
2" X 1/4" Structural Fiberglass Square Tube at ePlastics
ST-16L – Plastruct
Prescott Plastics 1 1/2” (38.1 mm) Square Plastic Plug Insert, Black End Cap for Metal Tubing, Fences, Glide Protection for Chairs and Furnitures (4 Pack) - - Amazon.com
Amazon.com: Prescott Plastics 3” (76.2 mm) Square Plastic Hole Plugs, Insert, Black End Caps for Metal Tubing, Fences, Glide Protection for Chair Legs and Furnitures (4 Pack) : Industrial & Scientific