Intarsia is a form of inlay introduced during the 13th century, possibly in Italy. It is distinctive from marquetry, in that Intarsia uses much thicker pieces of material that also include materials such as marble, metal, ivory etc.. It is not unusual for modern works to use pieces of material up to three inches thick.
The above design was done by P. A. Barney who provides plans for all his designs. His email address is above. I chose this design to illustrate Intarsia because it is a very impressive piece. The finished piece is 39" x 24" and it is made up of 221 individual pieces of wood. Using the plan, one simply cuts out each piece of wood with a scroll saw and the chamfers it to the shape required. Taken as a whole it would be a very challenging conventional wood carving, but the Intarsia technique allows one to tackle it in small, easily achieved steps. The reason why I have introduced Intarsia here, is because it lends itself to the construction of complex casting masters.
A suggestion would be to make the master from wood. Seal it. Lay up a latex open mould on it. Then lay up a two layer GRP backing shell. Then cast the item in hard plaster. Finish as patinated bronze.
Since the process is straight forward, perhaps it would be best to view examples af Intarsia by different artists.