304 Stainless Steel Square Rod Bar 3mm 4mm 5mm 6mm 8mm 10mm MODEL MAKERS Length 500mm Square Bar - AliExpress
Amazon.com: 2pcs 6mm x 6mm x 250mm Titanium Ti Grade 2 Gr.2 GR2 Metal Square Rod : Industrial & Scientific
Amazon.com: SHOUCAN 20 Pcs ABS Solid Square Rod Length 500mm Side Length 2- 6mm White Plastic Rod Good Toughness and Strength,5×5×500mm : Industrial & Scientific