Suggestions for Pot Risers

I made some specially curved slabs to go around my pond about 35yrs ago, I used some wire reinforcing in them and they are still good now.
I thought it best as I was using them as a few inches overhang on the liner.

 

I hope it works out for you @Februarysgirl , but yes - if the troughs aren't holding masses of weight, anything will be fine as a support.
I generally use bits of batten/spare wood, or even broken pieces of pot etc. My garden isn't level, so I always need a few bits and pieces for pots. My back garden is gravelled, so I can often just push some gravel under wherever it's needed.

That cement was well worth the strain on my back! It's a better 'recipe' than the stuff you can buy in a DIY store - it's much more forgiving. We're scunnered with all these workmen just now because they've been doing various types of work for at least 15 months or more, and they never remove everything from the sites. Cones, sandbags etc. If it's not the roads they're digging up, it's the pavements, and in this case, the field near us, at two sections, for water 'stuff'. That's about a year that's been going on.
They left the bit near the main road over a weekend so it was pouring water for three days before anyone came to sort it. I'd contacted the company on the Friday when I saw it, but of course, they'd all just b*ggered off early for the weekend and hadn't bothered to check that side of the field. What a mess - and what a waste of water.