Amazon.com: gazechimp 50cm Aluminium Round Tube Pole OD. Varies mm to 20 Mm, 8mm : Industrial & Scientific
Linear Motion Guide, FEYRINX 2PCS 6mm x 150mm (.236 x 5.9 inches) Case Hardened Chrome Linear Rail Rod Shaft for 3D Printer, DIY, CNC - Metric h8 Tolerance: Amazon.com: Industrial & Scientific