This is my first serious casting project. (I did some experimental zinc and aluminum casting when I was younger). I'm having a friend make me a western-style belt with a pattern of oak leaves and acorns. I figured it'd look sharp if the acorns were silver. That's how this whole thing started, I need some silver acorns. 

 Not being much of an artist, I figured the easiest way to make a silver acorn would be to copy the real deal. I went out and picked up handful of the smallest acorns I could find. I took these and sanded them in half. I used cyanoacrylate (superglue) to held them together during this process.

Then I cast a urethane RTV mold of these little guys.

Then I poured wax into the urethane and made the wax core-things. 

These I cast in investment plaster, melted out the wax on a hot plate under a terra cotta pot, and cast in lead to test the wax forms.

Here's what happens when you drink beer and watch pro-wrestling instead of paying attention to the lead melting pot warming up.

 So they look pretty good, and I'm ready to move on to the sterling silver. 

 Here's a quick overview of my home-made equipment so far:

Vacuum plaster setup. The metal tube is my flask and the white nylon is the flask base (to which the sprue is attached).

The pump is a Gast that we had laying around at work (that I borrowed).

The vacuum jar is a piece of ABS pipe that I turned on a lathe to round off the ID. The end-cap is delrin o-ringed with a push-lock fitting for the vacuum line. 

I trepanned an o-ring groove onto the end of the pipe so it'll seal against a piece of aluminum plate.

 This is basically designed around the 1.5" flasks I chose.

 I made some 2-branch wax molds for the silver.

I haven't tried melting any silver, but I'm afraid gravity won't be enough to fill the mold properly. Im thinking I'll need some kind of centrifugal casting machine. I'm planning on making that too, so I'll post details as I progress.

 Suggestions or ideas are welcome and appreciated!