[InnocentB]

Minor quibble: the box with the opening on top is a time machine. I don't remember any space-shipping happening with the use of props, it seemed to be all internally imagined.

[sp332]

Oh yeah, you're right. It was Pearls Before Swine that (recently) turned a box into a spaceship. http://www.gocomics.com/pearlsbeforeswine/2011/07/11

[zipdog]

Didn't Calvin once go to Mars in his red trolley?

[sp332]

He went to several planets and other (imaginary) solar systems as Spaceman Spiff.

[zipdog]

True, but did he ever use props as Spiff? Most of the time he was in the classroom with Mrs Wormwood