How about picking up a roofing or framing book from the library for
ideas? Unless you get an answer here from a qualified architect or
engineer, you may want to think twice before building and risking
children's safety.


Ditto, really.

To the OP:

I would have no problem building something like this, but I have also framed
a 2-story addition (which has not yet fallen down :-))

What you want here is engineering advise. The missing elements from your
question suggest a certain ignorance (I don't mean that in a nasty way at
all). It would be afraid that a bad assumption would be made by the you (the
OP) or by a replying poster or something lost in the context of a
text-only message.

It's absolutely a a DIY project, but get some experienced hands-on (more
than a keyboard) help.

-Steve