Well, maybe not easy… but certainly far more straightforward than you thought.
The concept is simple: you take an Arduino, some servos, and a 3D printer, and you build a spider-like robot (commonly known as a spiderbot). At the end, if all went well, you should have a robot with four to eight legs, capable of walking around. Rather than being remote controlled (which is an option), these robots are typically programmed via an Arduino sketch.
Want the spiderbot to wander across the floor to scare your pets? Simply program it to do just that. As long as you’re familiar with creating and editing Arduino sketches, you should be able to manage this or at least edit an existing sketch.
Getting to this stage can be challenging, however, without the right design, and affordable tools. In the video above, Hari Wiguna talks us through how he did it, with a job lot of servos for just $23 (which would come in under £20), an Arduino Nano (a Nano V3 Prototype Shield is also a good idea) or Arduino Mini, and a 3D printed body and legs.
The originator of this 3D design is Regis Hsu, whose Thingiverse page features around 12 different designs, including a variation on this spiderbot. In the interests of completeness, Regis has also provided a detailed build in this Instructable, where you’ll also find the Arduino sketch for programming the spiderbot.
Of course, this is just one spiderbot of many. A quick search on YouTube alone yields results for a GoPro camera robot, an army of spiderbots controlled by Intel’s Edison chip, and any number of spider/insect-bots with numerous combinations of legs. The ideas are out there for you to follow, and take inspiration from!