Don't.
Instead, create an event (call it SaveRequest for example) in form2, which form1 handles - it can then decide how to save. If you start accessing controls from outside the form, then you tie the designs together and you can no longer alter one without considering the effects this may have on any other forms that might use it.
Creating an event is easy:
A simple code snippet to add an event[
^] - all the code you need is right at the start, the rest of the tip just makes it easier to create them!