There is no better way to learn electronics and robotics than building your own robots. Spiderbot V2 is a 3D printed transforming robot driven by Arduino worth building. It has spider and vehicle modes of operation. The robot can be controlled using an Android phone. Body, tibia, femur, and other 3D files have been made available by Smudger_WTH.
You are going to need an Arduino Pro Mini, 12 servos, Adafruit 16-channel servo driver, Bluetooth HC-05 module, and a few other parts to complete this.