[50mm]

I've been eight miles high.

And when I touched down,

I found that it's stranger than known.

[shibumi]

I just read some of the other posts on this thread which in turn caused me to look up a couple of other cases.

There are at least two people who have exceeded 15,000 feet altitude by strapping helium balloons to their lawn chairs.

Hmmmmm... Let’s see now...

Homemade rocket?

Lawn chair with balloons?

I’ll take Lawn Chair for the win Alex!