Surround for a preformed pond

My husband dug the hole in the summer and fitted a preformed pond. It has an undulating shape. My problem is how to surround it so that the edge is neatened up because at the moment it is getting warped and doesn't look very attractive. He has just bought some paving slabs but is now agonising about how best to fit them. Any ideas please. I have completed many searches on the internet and found very little inspiration.

Have a look here for some tips/inspiration:

http://www.pondexpert.co.uk/edgingyourpond.html

What sort of edging stones is he using? If it has an undulating shape the stones would be best if they were irregular and fairly heavy to sit on the warped bits. Have you looked at pages like this?

https://www.google.co.uk/search?q=garden+pond+edging+stones&hl=en&source=lnms&tbm=isch&sa=X&ei=CVZGUfrHG8O1PMTAgdgM&sqi=2&ved=0CAcQ_AUoAQ&biw=1192&bih=514

The main purpose of stones around a pond, and hard edging, is to hold down the edges of a liner.

With a pre-formed pond that shoud be not be necessary.

I like to have plenty of plants around the pond, so that small animals can get in and out in safely. If it's a preformed pond you could run grass right up to it.

If the pond is warping, then I suppose the best thing would be to find out why, and do something about the cause. Maybe some more support is needed beneath part of it. Or a little bit more soil needs to be taken out from somewhere.

Stones around a pool are not just to hold down a liner. They are decorative too, and big irregular ones provide hiding places for creatures like toads. There should be a place for creatures to get in and out. Some preformed ponds have a bit of a lip which is ugly if not covered. Look at the difference.

Thanks for you input. I will pass your suggestions on to my husband and if can work out how to do it I will post a picture of the pond.

Lyon's point is important. It could crack if it's forced out of shape by not being supported. Putting slabs round could make that worse.

I would support this sort of pond liner by washing sand down around the edges with a hosepipe until I was reasonably sure that all the voids underneath and under the surround were full of sand. (You would have to do this with the pond full or it would tend to float!) To help with this I would dig the hole about 6" wider all round than the liner itself, and make sure the hole was deep enough that the top surface of the surround of the liner was flush with the ground, which would help when you came to lay stones around it.