To be honest, I would look into saving up for a dutch oven, and just cut your milk jugs up into small pieces, say using a blender, and then dump them into a dutch oven, and stack it with coals. Those puppies get super duper hot, and I think you would be able to melt it down sufficiently. enough to mould it. You could even experiment with making aluminum moulds and placing them inside the oven, and seeing what happens.
Hope it helps, if not, at least you can make some sweet cherry cobbler, and you can always just go with cutting boards.
I'd try the dutch oven though.