Slotted Aluminum Extrusion - 20mm x 20mm - 610mm long : ID 1221 : $7.50 : Adafruit Industries, Unique & fun DIY electronics and kits
EXM-2020-BLACK – 20mm x 20mm BLACK Smooth T-Slotted Aluminum Extrusion | TNUTZ
2040 V-Slot Extrusion 20 Series - 20mm X 40mm X 1m - Black – 3D Printing USA
Amazon.com: 20mm x 20mm T-Slot Aluminum Profile - SANTIE 1 Piece Cut to Length 1300mm, Silver 2020 Extrusion with European Standard Linear Rail : Industrial & Scientific
Amazon.com: 80/20 Inc., 20-2020, 20 Series 20mm x 20mm Extrusion x 610mm : Industrial & Scientific
20 Series, 20mmx20mm T slot Aluminum Framing Extrusion