We use a *lot* of salt in our art work. Either for salt & glue paintings or simply to be mixed in paint to give the grainy, sparkly structure. This time we made salt castles! I got this idea from Fun At Home with Kids and here's how we went about it.
Add 1 teaspoon (5ml) water to every 1 cup (250 ml) of table salt. Mix thoroughly and fill up your sand moulds. We had one conical one and two little castles (the rest magically disappeared). We left it to set overnight. The next day, I stuck a tray/plate to the open end of the mould, flipped the two 180 degrees and then removed the mould. The salt castles came off the moulds immediately.
It was ready to be painted via droppers /pipettes. Good fun for both toddlers & preschoolers!
My philosophy for any project is 70:30, i.e. at least 70% of the work should be done by my kid with a maximum of 30% assistance. Here however, I did the mix and flipping while he helped fill in salt in moulds. He did the painting all by himself of course.
We "preserved" these castles for a few days before tossing it in the bin!