How to make a single mould?

As I have been making moulds the last couple of days, I'd thought I'd share with you how to make them. Moulds are very useful for repetitive tasks for example if you work with polymer, paperclay, ceramic clay, papier maché,...
Making a mould is not difficult, it's just a bit messy so you better have everything you need prepared beforehand.

This is what you need: plaster, empty icecream containers, liquid beeswax, clay, scissors, knife, doublesided tape, tape, modelling materials (only if you mould claywork), paintbrush, water, towel. Be sure to protect your surface with a plastic tablecloth and wear an appron if you're messy.
I'm going to mould an existing bowl. A bowl is an easy thing to mould. That way I can make loads of bowls like this...
Put some doubleside tape on the edges.
Press the bowl onto the placemat so that it sits firmly. Now no plaster can go on the inside of the bowl.
Since you'll be putting plaster on the bowl, it will need to come loose afterwards. That's why you need to put some beeswax onto the entire bowl. If you use clay, you don't need to do that as clay is cellular and will come off easy.
I always safe empty ice cream containers as they come in very handy for moulding. Besides, it's a good excuse to eat icecream. :) Cut off the upper part of the container and place it over the bowl.
Take some clay and press the clay firmly around the container. This way, no plaster can escape.
Make the plaster ready to pour in the mould. The plaster is good if it has the same viscosity then yoghurt.
Place your hand above the bowl and pour the plaster via your hand into the container.
Let it set until it's hard.
Take away the clay and try to get the real bowl out of the mould. If this is hard, you can hold it underneath running water so that it's easier to get it out. Let the mould dry before using it.
If you have left over plaster, don't throw it away but poor it into a container and let it set. You can do fun mouldcarving like this.

Next time I'm going to show you how to make a double mould so stay tuned! :)