First 10 mm building casting attempt

Given the limited choice in 10 mm WW2 buildings and the poor coherence between different suppliers' models I decided to try and cast my own.  This means build the original. make a cast, and cast different units.  Of course, I want some variety.  I decided to go ahead and attempt a row house front first.

 I started out by making a complete 10 mm two store building in Normandy style.  That was my first mistake.  I had to rip it off of the plastic board, and the glued construction is far from stable, considering you need to exert some serious pressure to get your detail in there.  The second mistake is the use of architect board.  Way too soft, impossible to smooth before casting, so you have a lot of cleaning up to do afterwards.

I tried to make the edges are clean as possible, added a little frame for the door, and then started mixing the silicone paste.  This is a putty version, that goes very soft when mixed together, and is really easy to blend.  The detail is superb.  That was the first problem with the mould.  I cut out the holes for the windows without taking into account the depth.  Some of the shutters are not perfectly against the wall.  Not a problem for a one off, but a big issue for a mould: putty creeps between every nook and messes up the finer details.

Another issue: the edges.  You really need a box to push your putty and original into.  I grabbed a bit of flat board just to make sure I have a straight bottom on my mould, but that's only 50% of the story.  First impression the mould looks great, but on closer inspection there are a lot of areas where the putty crept into small crevisses.  I tried to repair this but obviously this wasn't easy.

Nevertheless I cast a row house front in my new mould, and the result was not too bad.  For row houses, you just need fronts and rears, the rest can be architect board.  If you zoom in you'll see the zones where I had to perform repairs, some missing detail, and some bubbles (I forgot to take care of these) but it is also clear that if you have a good original, the mould can be amazing.  I'm gonna paint this one anyhow just to see how it looks.

So from here, the next step is making some clean originals.  I am thinking about making parts that are multi-use, like two windows, a window and a door, a shop window, three windows, so that I can assemble houses with little effort.  In order to have clean edges, I'm gonna look for 3 mm thick plastic board.  You can get a perfect edge on those, they can be sanded, scratched into, and so on.  Alternatively, I could use 2 mm board and put a nice flat layer of white milliput on it, so that I can sculpt in brick details and textures.  That should keep me busy for a week or two.