We are always on the hunt for a better and easier ways, not to mention cost effect ways of crafting.
A customer recently told me about Gibb Plaster of Paris for use in the IOD moulds. Only like $10 for a 5kg bag. Fortunately I had purchased (hoarded one) well in advance of the Lockdown, with every intention of trying it out....hellow Lockdown.
It is messy to use. Mix it up with water, allow it sit before you pour it into the moulds.
Fill the mould with the runny liquid then smooth it out with a ruler or credit card.
Allow to air dry or stick it in the oven to dry.
I found they did crack if I tried to take them out before they were fully dry.
The detail from the casting is much clearer than with air dry clay, which is always great. There a few small air pockets in the moulds. It was a long process as there is not much you can do until it has dried.
It is a great option for making stand alone moulds. Again any glue can be used, I used the usual Tacky glue, a lot of it.
The advantages are great detail and solid moulds. They won't crack later creating an unpredictable finish, you will know what you have once it is glued, unlike air dry clay which changes as it dries and can crack unexpectedly.
They felt more like authenic plaster moulds.
However, it is messier, and you can't really start your project until it has dried.