Janet
I’ve used Delft clay over the years, and you are going to have a
hard time with this plan.
You cannot use wax to make a model here, as you will not be able to
burn it out of the clay like you can with a plaster flask. What you
will need to do is create a model in something robust (possibly
metal, this is called a pattern in the literature) which has no
undercuts so that you can manually remove it before you pour. You
will also want to use a metal which flows very, very easily, so gold
rather than silver, and have a long sprue so that you can get some
pressure behind the pour. Do some searches on industrial founding, as
that is the kind of thing this technique lends itself to on a smaller
scale.
There was some interesting stuff done on creating a pattern using
Styrofoam and leaving it in the clay, as it can burn out as the
metal is poured, but that would require pretty high tech tooling to
do on a small scale, not to mention the hazmat issues surrounding the
burn off.
Good luck.
CP
Collarsandcuffs.co.uk