Here's a simple way to make DIY durable molds using inexpensive ingredients.  In this instructable i used my adjusted sticky playdough recipe.

I am making a large boquet of cold porcelain roses and was thinking of ways to make them faster. 

There was the option of using silicone molds or plaster paris.  However, I was a bit unsure how safe silicone was to handle and plaster paris usually ends up pretty messy.

So I settled on sticky playdough. This sticky recipe picked up all the finer details from the leaves I was casting. And the resulting leaf impressions were surprisingly clear.

Step 1: Sticky Playdough Recipe

Normal playdough recipe is quite smooth and malleable. 

However with this sticky playdough recipe, what makes it great for casting is that it is so soft and will enventually dry rock hard.

Instead of a ratio of 1:1 flour and water mix, I add half a cup of extra water.

2 cups plain flour
2.5 cups water
1 tbl tartaric acid / bicarbonate soda (adds bounce)
2 tsp teatree oil / orange oil / nutmeg oil (kills bacteria and prevents mould)
1 tbl salt
1/2 cup lime (calcium carbonate hydrated)

I lowered the amount of salt in the recipe as it has a tendency to create holes when drying, but there is a smooth finish when I added lime powder for some reason. You could chuck in some crushed Calcium tablets if you don't have any lime powder at hand.

Step 2: How to make an Impression

I covered the back of several leaves I collected with a generous coating of mineral oil.

The back veins are deeper on the leaves than the front and are perfect for casting.

Roll out a piece of clay that is larger than your object for casting.  Here I rolled the playdough onto baking paper and pressed it flat with a piece of plastic wrap.

I then pressed the leaves into the sticky playdough.

Step 3: Check the Cast

Voile! Here's some lovely, detailed leaf impressions that worked on my sticky playdough recipe. I think I'll try it with DIY polyfilla next.

Air dry in sun for a week. Once hard, I'll impress another set of sticky playdough for a reverse impression.

Watch the live clip for more details.

food grade silicone is perfectly safe to handle
<p>yea and makes a gr8 release agent for any mould in that temperature range</p>
hi, it is a good idea but if you use cold porcelain <br>dough or salt dough it will not take that much time<br>to dry <br>the cp will take about a day <br>and the salt one but it in the oven<br>the thinner the leaf the faster it drys <br>
Thanks for that! I'm still experimenting with CPC, and its a lot harder for me than it looks. You instructables are quite helpful too!
use han solo in carbonite toy instead of leaves and use sticky playdough for mould and once dry poor in melted chocolate
Flour/salt doughs tend to be porous (and leach salt) so the chocolate would stick (and licking it off the mold would taste nasty). The cold porcelain might work better, a vacuum former could create the same molds that you can buy at the candy store.
thanks for your comment, true the salt on chocolate might taste bit funny, but I'm not sure pva is safe to ingest - particular some glues made o'seas might include formelhyde not safe for those expecting. otherwise all the ingredients above are pretty safe with chocolate
The trick would be pulling the chocolate off the mold.
interesting concept, all the ingredients are safe, except too much of the ca hydrate, may cause stroke

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