You know it's funny, I was about to suggest something involving Lisa's dolls or doll house then you drew this. Funny thing is if memory serves there was a little tiny Lego suitcase that opened and closed, I wonder if that's what Bart's using there.
I wonder what will happen to Bart when Lisa's friends arrive.
Sherri: Dress up time Bart!
Funnily enough although the concept of the walking robot has been around for a while, by which I mean decades, it's taken until maybe the last few years to actually make a real full size one that can walk up and down stairs or a slight incline without falling over.
Turns out walking is harder than it looks.