I've never even eaten one, so I had to look it up. It's ok to eat the whole gauva, seeds and all. Just rinse it off, cut off the ends, and munch away.
But my son likes guava juice, albeit the kind you buy in a can. I don't own a juicer or anything fancy like that. So I thought I'd try to make my own with basic kitchen equipment, a blender and strainer. This instructable documents what I did.
Apparently, the guava is more exotic then I realized. The spell-checker wants me to change guava to cave.
Step 1: Ingredients and Tools