Creating a Portable App?

I've been through most of the documentation and from my reading I should be able convert a existing opensource app into a portable app correct?

It would be very helpful if there was a practical example of taking a non-portableapp and turning into a portableapp.

The existing documentation is very detailed but its difficult to assemble it into a functional example of creating a portableapp.

If there are any functional examples out there on how to create a portable app, please point me to the right references.

Thanks!!