Stonecasting, or fibrecasting depending on what name you use.
This is a 'relative' new thing. Basically it's a fibreglass (usually) pots mixed with powdered limestone or other ground up stones. Giving the look of a 'genuine' stone (planter) pot with the durability and weight similar to fibreglass products.
(examples to be found http://www.articolestudios.co.uk/pixs/mouldmaking4.jpg and http://www.taylorsgardenbuildings.co.uk/store/images/d_7984.jpg )
I was quite shocked at some of the prices being projected to me for fibre glass products in my vicinity. On the other hand I (somehow) can find miraculously cheap 'fibrecasted' pots in the region. I do have some contacts with the manufacturer and he's very willing to make some custom designs. I'm just scared at this point that mixing limestone might affect my PH values.
Usually these pots are double coated in and out with resin, would it matter at all for a AP setup to use stonecasted tanks?
AP thirdworlder on a freaking budgetttt
makes setting up systems even more fun
Or depending on how cheap you could get the fiberglass tanks. I would go with them minus the stone. You could always build a wall around it to make them look like they are made of stone. Without any leaching problems ever.
