How would you make a pond in this?

[Manchmallehrerin]

I am trying to turn half an old copper tank into a patio pond. To hold a single mini waterlilly...

I am stuck with how to edge the top, it is a sharp metal edge and I am concerned it will cut through my liner? Also I am stuck on how to make a beat finish? Any ideas?

Thanks in advance

Can you turn the edge over, like a hem?

Though this may sound negative it's always going to look exactly what it is... half an old tank! By a "beat" effect I assume you mean hand beaten. The problem is that when you beat a piece of sheet material into shape using dollies and ball pein hammers its sharped by thousands of blows. Just beating it with a ball pein wont have the same effect.
If you do want to do it: First trim the top of the tank square. Second mark a line about 40mm from the top inside and out, use a reaction block on the inside and a hammer on the outside and start forming a flange by gently working round. Don't be tempted to go too fast and strike it too hard, you'll distort the tank. If you want a hammered finish use a ball pein hammer on the outside as a reaction block and strike the inside of the tank with a second ball pein. This will take an age to generate the finish that you want. Again don't be tempted to work too fast and strike the tank too hard as you'll distort it.

Thanks for the advice - I am happy with it looking like a tank - I have made a typo with beat - I meant best - although a beaten finish would be nice I don't know if I have those skills.

I was thinking more of wrapping the edge in trip to protect the liner and then make some kind of rim to fit over the top?

Folding it in would make the nicest edge - but I am not sure how to fix the liner?

The foam stuff you use to insulate pipes would cover the edge. It's a foam tube with a slit along the length.

Yes I'd go with pipe insulation (for 15mm pipes) that's a good idea and inexpensive too. Do you even need a liner?

An old hosepipe split along the length would also work to cover the edge.

It is very steep sided so any small animals falling in e.g. hedgehogs would not be able to get out.

Not sure how one would get in though.

Presumably you want the top to remain decorative or are you taking the liner all the way up and over the top?

If you are wanting the top to remain decorative I would use thin flexible copper strip. Take the liner up level with the top of the tank and then superglue in place (make sure you've put the water in first to get the liner level right so that it doesn't pull). Then use the copper strip to encircle the top of the tank, folding it and pinching it in so that it covers the liner edge and the tank edge.

You can buy pond silicone which bonds (used for repairs), you could run some around the rim to take the sharpness off and it will also glue the liner in place. Or run normal silicone first on the rim & let it dry.
You will have to get a thin liner as it can be quite heavy and thick, you will get lots of ravels trying to place it in the narrow bucket.
Try marking out with an old bedsheet first to get an idea of size and shape.
Look forward to the after pictures.

Could you put in some metal mesh that would be submerged when the tank is full, and the lily can grow through, but that would help any birds get out?

@HasaDigaEebowai copper tape! Thank you! I didn't know this existed - just what I need.

I don't think I need to worry about anything climbing up - It is 65cm high and I'm not going to sink it. I will think about how best to stop anything falling in from above...