Tracktor robot with place for electrnics
This is a model I made for my youngest son.
There's a place for a battery box, a 4x6cm proto-board, a power switch and a led on top of the head.
Mine has a 555 IC that blinks the led and is printed in a really beautiful wood-filled PLA.
Everything prints without support (body and panel have built-in support), most of the parts don't need any infill, print 4 wheels and 1 each of the other stl files (I recommend high infill for the wheels).