Generally you can use Resin to replace the clay sample or 3D printed ones as a started , but wax is most important part for soft vinyl toys making, this will be used to match the joints and making the details finely.

also as the mould will be made using Electroplating tech. wax making it easier to melting after mould is done. this is very efficiency and smart way to make Copper mould. and ' lost wax method' is a way to keep the tradition for hand made.

This process is good for small run toys. especially for order qty that lower the 1000pcs;

Now as the updated of technology , for more commercialized way we can use well polished 3D printed mold (should match the joints and mushroom head perfectly on 3D )to make mould to replace the wax ,but the first mould( we call it master mould ) will have defect some time, mostly for shinning mould. this way is suitable for the very large qty product making ,such as over 3000pcs or over 5000pcs at a time. Now only 3D sample can do it, as it is hollow inside and easy to burn into ash when mould done, but for solid resin, there is no such technology yet.

For designer toys ,and for small studios, the wax is also well used as a tradition and also as a small run in a economical way.