This here is pour number one, the failed pour. The wood brace is to hold the head in place, so it doesn't fall over within the mould while i'm tapping the thing against the table (trying to remove bubbles).

Here's some technical stuff, in case someone reading this is going to do the same thing, and doesn't want to repeat the expensive mistakes.

The interior dimensions of the above mould is about 5"x4". The alginate came in 1 lb bags (about 30$). A 1lb bag would do two + of the above pours.

The ratio I used was 1 part alginate to 1.16 water. It was a little thick; about the minumum amount of water I would use. Specifically, I used 650ml alginate to 750ml water (cold). Then I mixed the hell out of it with an electric mixer.