Following this with interest..
I'm also planning to dig me a small pond next year or so.. Also had thoughts about a raised pond with infinity window. But to make that realy solid, long lasting and fool proof it definitively needs to be a la
@frederick thompson style, concrete, bricks and polyester coating. Any other way with wood and liners etc, i think it wont be a long term success.
Concrete etc. ever lasting if done correctly but a major and rather expensive undertaking. And my personal draw back it's hard to make it look realy natural. At least in the small size i have available it might just look to bulky. Thus i think for now i go with diggin an hole and use epdm liner. I still have a year to brainstorm and gather ideas and inspirations.
What actualy pulls me over the line(r) to go diggin is the simplicity in building a very (cost) effective filter system for it. i'm definitively will give this principle a go.
Only thing is it needs to be sized down to fit, since i'm not planning to build a dip pool. But regarding the technical aspects, its the most effective and cheapest filtersystem we could make. It runs solely on a simple air pump. Can't have a beter relative maintenance free filter system build in the pond itself.
What i find also very inspirational are the video's from PondGuru.
The way he hides the liner with the use of edging stones and at the same time creates a wildlife invironment under these stones for amphibians etc the hide under it.
The end result is very natural and aids the development of a healthy biological invironment
Another pro in that air driven under gravel filter system, is microbiological organisme such as the crustaceans in the water column are not sucked in and shred to pieces by an impeller.