wait for a finished mould matey with the original items in.
however………the plasticine holds the models in place so that you can lay the rubber up to, to make the first half of the mould.
then you leave the model half embedded in the rubber half that you have poured into the box, and peel away the plasticine and put it aside to use next time.
you leave the half moulded rubber in the box with the model half embedded in it. rub Vaseline over the exposed rubber around the model embedded in it, and then pour the second half into the moulid box covering the model and the already set and cured 1st half rubber.
have a look at one of the lifeboat men both outside and inside the mould for a visual explanation.
so in the pictures below the man would have been sat in a box originally with plasticine covering half his body from head to toe whilst sat on his back and the plasticine moulded along the body length imagine in this shot, that the rubber is in fact plasticine.



and the view above shows the cut outs to where the resin is poured into.