1/2" x 4' Heavy Wall Square Clear Plastic Tube | VisiPak
Clear Extruded Acrylic Square Tubing (1/16 : TAP Plastics
Amazon.com: Prescott Plastics 1 1/2” (38.1 mm) Square Plastic Plug Insert, Black End Cap for Metal Tubing, Fences, Glide Protection for Chairs and Furniture (4 Pack) : Industrial & Scientific