The vacuum is not necessary here, something this simple is achievable with sand casting (search for "Delft Clay") and a bit of practice. Ensure the sprue is wide enough and air channels are plentiful, make sure the metal is as hot as it's possible to get it, and pour swiftly in one fluid motion.
The snag is that you need about 3X your desired weight in metal, which in gold is... probably more expensive than the vacuum casting setup! So maybe the above applies mainly to silver unless there's a good use for the rest of the gold.
The snag is that you need about 3X your desired weight in metal, which in gold is... probably more expensive than the vacuum casting setup! So maybe the above applies mainly to silver unless there's a good use for the rest of the gold.