I recently saw a demonstration of an inexpensive casting system.
The Delft system. It comprises two small aluminium rings about
2" diameter, 2kilos of clay, a 3" crucible and crucible holder.
One of the rings is packed with clay and smoothed off, the
pattern is then pressed firmly halfway into the clay. The two
rings are aligned together and clay is packed into the other
ring covering the pattern. The rings are then taken apart
revealing the pattern which has made an impression in the clay.
Air holes and a hole for pouring are made in the clay. The mould
is put back together again. The metal is then heated and poured
into the mould. When cool the mould is taken apart. The casting
is taken out and cooled. The clay can be reused. Just like
making a cake!! If anyone is interested I can give you the
Silversmith & Jeweller