The first time I saw one of those I was enthralled! I thought it was super-trick to have the fish swimming above the pond's surface, which it is, but the reality is you have to be prepared for quite a bit of hassle. I agree with what's been said above in that Youtube would have the best tutorials on the subject.
I think it would be amazing to have an inverted aquarium at the edge of my pond where the fish could swim at say, table height and come and go at will, but thinking it through I know I am too lazy for that kind of an attraction.
This is not intended to discourage you, and we would love to follow your progress through the building stages! Were I to attempt this I'd also include lights that would illuminate the area at night giving the illusion of the project floating above the pond.
The distractions for me would be....as Lisak1 mentioned, the algae would build up quickly because of the sun, not to mention the water temperature which may be a hindrance to the fish. Maintaining a vacuum on a volume sufficient to make the "bubble" size worth the effort may be problematic. If this is to be permanent some method would have to be devised to allow water to circulate through so the water didn't get stagnant - this may aid in lessening the algae and temperature rise, but it would have to be engineered so that no air whatsoever could collect in the top thus compromising your vacuum and water-holding capabilities.
What size had you envisioned? Please show us your progress! We don't mean to dampen your enthusiasm for something out of the ordinary and are willing to help if we can.