Mould making tutorial, Part 5 - dents and holes

There are two things I really should clear here, before going forward with my mould.

First - how do I make those sphere-like syncronization details, that'll fix mould sides to each other? I use two kinds of tools for this.

I have18 part steel punch tools set, with sizes from 3.5 mm to 16 mm. I'm using them for sculpting, whenever I need dents or cavities, and also when I'm making silicone parts of the mould. Two of them are visible on the next photo.

I have also 2 other tools I made myself from epoxy putty. They are like miniature "cookie cutters" and I'm using them when I need half sphere details. I made them for making 1:4 scale eyeballs (smaller has diameter of 6.5 mm = 1/4 of 26 mm) , but they work very well for making details for moulds.

Secondly - how does silicone get inside the plaster?

There should be hole inside of silicone to get resin in. And, there should be an hole inside the plaster to get silicone in!

One way to do it, is to press some sort of tube, like the one inside of paper towel roll, to the clay before covering it with plaster. This way there will be a hole inside of plaster to pour the silicone in. There are holes like this in my Werewolf's mould.

On this mould I'm making now I hope to get the silicone in without the additional hole, from the opening on the one side of the plaster. This mould is just small enough, I hope silicone will flow there and fill it. If this doesn't work out, I still can drill the additional opening.