A Friend of mine just conacted me on melting NSP and wax based clays - All regular plastilines can be liquidised, the problem is - they all remain kind of gooey (all I tried - if you know of one, pleeeease let me know!) - which causes problems if you are trying to reach into every fine detail of a mould. “Autostyle clay light” is a discontinued product, which was a wax based clay with added fillers to make it light and malleable.
There are many light clay like that, like the one from Kolb (except TechClay), or P60 - everyone claims they can be melted and poured, but every kind I tried so far did not get as runny as the Autostyle (runny as double cream) or they separate
However, be careful when pouring NSP or a light clay - don”t overheat, make sure you are wearing appropriate protection (this stuff is nastier than hot glue and people have been SERIOUSLY burned) and make sure your mould is nice and hot to avoid nasty tidelines. You can also use a hot air gun for your first layer and paint the liquid clay into your mould.
if you want to reinforce large pieces, only pour a skin of clay, place a bin-liner in your mould and fill it with biscuit foam - having the bag around it helps the clay to stay free of crunchy bits that the foam creates - also, it makes your cast relatively light…
