First I added three little "legs" on which the engine can rest when pouring the silicone.
With these legs the engine is a few millimeters above the ground.
Next I began to build the box for the mold.
To save silicone, I tried to make it as small as possible.
I sealed it off on the ground with some clay that is silicone resistant.
Then I sprayed the actual engine with some mould seperating agent.
I made very good experience with this 1:1 mix silicone from my favourite shop (http://www.rai-ro.de/english/katalog/seite14e.htm) which is very easy to work with.
First i poured the lower half and again I used the clay to make some alignement marks.
Once it cured I did some cleanup (removing the clay, as well as some stray silicone on the model).
Then I applied some siliconeform seperating cream, to ensure both halves of the mold will later seperate easily.
Then I enlarged the box, and poured the other half of the silicone.
The silicone cures rather quickly so after two hours I removed the box.
Then I seperated the two halfs of the mold.
The model seperated easily and without damage.
Then I used some more clay to close the three small holes form the legs.
This can also be found at Ria-Ro (http://www.rai-ro.de/english/katalog/seite15e.htm). Again, since it is a 1:1 it is very easy to handle.
So I poured the first half of the mould (and some excess that I had into the other half).
Once the first half was cured, I poured the second half - applying a thin fresh coat on the first half.
And then I placed the first half on top of it.
And put som rubber bands around it to keep everything in place.
Unfortunately the resin is allready a bit aged (more than 12 months), and it seems it either didn't mix completely, or it simply didn't cure anymore....
At least the mould is working properly and I can try again. I will give it another try tonight with the same resin and hope that I just made an error when mixing, or if it fails again, I will have to order a new batch of resin....cross your fingers for me.