Another Christmas present was this, solar powered mechanical machines.
The main motive module builds up into a block containing motor, gearing, and a solar panel for power
To this can be added a variety of walking, floating and wheeled structures, this a fairly standard wheeled carriage.
I would have posted a video of the thing moving, but the weather is too dismal to power it at the moment. Though a bright lamp held close has proved that it will work. Expect ad hoc postings of various forms functioning come the summer months.