Plaster of Paris is a good medium for making moulds for just about anything. If you want to make a mould for garden ornaments in the shape of a dragonfly, for example, you will need an item the correct size and shape for you dragonflies. Once you have made your mould, you can make as many garden ornaments as you like.
Slather your item, such as a toy dragonfly shape, with vaseline. Your item can be any shape of your choosing, but it must be coated with vaseline.
Mix plaster of Paris in bowl with water according to directions on the box. Pour plaster of Paris into shoe box.
Press your item into the plaster of Paris. Do not press in all the way; press in about halfway. Make sure it is enough to make an indentation in the mixture. Leave the item in place and allow the plaster to dry. It is best to leave overnight.
Remove the item from the plaster. Wipe away any excess vaseline with a soft cloth. The indentation in the plaster of Paris is your mould to make as many garden ornaments as you want, one at a time.
Smooth, nonporous items for the mould work best. Plastic sandbox toys, bowls and clay or plastic sculptures are good choices.
When you make garden ornaments with your mould, remember to apply vaseline to the mould again before pressing materials, such as clay, into it.