Air dry clay is dense & holds very fine detail well, perfect for these moulds.
Knead a small ball briefly in your hands to eliminate any cracks - make sure it is very smooth, then press into the mould making sure that all area of the mould are covered. Once you have done the 1st one you will know how to do it. If the moulding does not work, roll into a ball & do again. the paper clay must be pressed into each little piece of the mould.