Quantity   Component name
20 × Steel square tubes 20x20x2000mm, 2mm wall thickness 100,-€
10 × Flat iron bars 20x4x2000mm 30,-€
400 × Screws M6x10mm 25,-€ Preferably with round head for hex or torx tools
100 × Nuts M6 10,-€
400 × Split washers M6 10,-€
45 × Ball bearings 10x30x10mm 30,-€
10 × Ball bearings 6x19x6mm 10,-€
3 × Threaded rods 6mm, 1m 10,-€
1 × Sheet metal 300x500x0.75mm 10,-€
1 × Plywood 300x600x5mm 10,-€
1 × Arduino Uno 30,-€
1 × 12V Relay 5,-€ Router on/off
2 × double H bridge L298N 10,.-€
3 × DC motor 5-12V e.g. from an old Printer or scanner
1 × Small parts like cables, tin-solder, resistors, transmissive optical sensors 50,-€
1 × Total costs of around 350,-€