10 Pieces Hollow Metal Cavity Fixing Hollow Door Anchor for 0-5mm Door Extra Short Hollow Wall Anchors Aluminium cladding Sheet Steel Pipe, Iron Sheet, Hollow Plastic Sheet (8 * 16MM): Amazon.com: Industrial
2PCS 5mm to 8mm Aluminium Plum Flexible Shaft Coupling D20 L25 Connector Flexible Coupler for 3D Printer/DIY Encoder and Servo Stepped Motor: Amazon.com: Industrial & Scientific