Here are pics of casting my tiger rump. These were used in an article a gal on an artsy fartsy forum I used to frequest did around Halloween one year. I may or may not be able to find that link... it was a few years back.
My poor dead Tiger Rump, buttless. He was a good little T, unfortunately males are much shorter lived than females.
Melting a wax sprue on dead T's body- this is the channel for the melted silver to flow into the cavity
In the base mount and in the flask
This the silver button, after the T has encased in casting investment and then burned out in the kiln. You ramp up the heat over about 2 hours per temperature incrementt, to what the temperature of the metal you are using is in it's liquid state then let the flask soak in the kiln for several hours. You have to make sure whatever is inside has enough time to burn out completely before you try to cast- most organic things can be used. Often times skulls tend to have a thicker area that does not burn out which will leave an area inside the investment cavity where metal can not flow and/or the liquid metal will encase the leftover part, probably leaving some of it exposed.
The cast tarantula, after it has had the majority of investment removed. Basically, you give the flask time to set, until you see the metal button has cooled to a non-glowing state, then you quench it _we use a 10 gallon trash can) and the bulk of the investment boils off in the water.
Using my Foredom, I cut the cast piece from the sprue and grind down and blend the gate, then depending on the item I have cast, tumble it in stainless steel shot or use my ultrasonic tumbler (designed for preserving detail, it uses basically small pieces of guitar string for the tumbling media). In this case, I use the ultrasonic tumbler and burnishing liquid.
Then of course, give my T a butt and he is memorialized forever in sterling silver.
Well I found the page on the forum where I originally posted pics back in 2009 but I can't find the lady's Halloween blog article. Oh well. :)