Pam that looks good! Is that like solid clay or something?

Maybe its the pic but Im wondering if its really 2000 gallons?

I dont work for Helix but I saw one in person once along with some other brands and it does look by
far the best deal around in terms of size, unique design and heavy duty materials and
being fish-safe - esp when you consider that any brand is going to be in
the 300-500 range anyway

If it was a small pond then there are smaller skimmers at less cost but a 2000 gal I think Id go for a good size skimmer - esp if theres trees/debris nearby.

I thought the same as current resident. I admit it is hard to mis-measure so much, but it appears to be something like 6' by 12' and I am assuming 36 referred to depth in inches. If you really did mis-calculate then you wouldn't need as large a pump. I don't have a skimmer. I always wonder if a skimmer will do much good if there are a bunch of plants in the way. If plants are small and on your shelve edges, I suppose it will be fine.

You might want to search on older cliffandjoann posts and any waterbug_guy posts for thoughts on filters and everything else. Waterbug_guy has all sorts of thoughts and varied experience although I don't think he is participating currently. Joann still keeps an eye on this forum.

You can make all sorts of things for yourself. You don't need any professional underlayment (old rug works great) and your specific hole probably doesn't really need anything under the liner. Filters and skimmers can be home made.

It looks very cleanly dug out. The only thing I can comment on is that with all those different shelves you will have a lot of difficult wrinkles to work with in placing your liner. Maybe consider removing the inside two levels and just keep the apron in front of the falls and the shelf around the perimeter? I have had shelves fall down under the lining so I quit making shelves and just put milk crates with large flat rocks on top of them to hold my plants. It also gives the fish a place to hide in case of predators.