Now there a a new option, Instant Mold or Oyumaru both works the same, Instant Mold is more expensive but easier to get.
This how it works.
This is the Oyumaru this pack cost me around €6 from a ebay seller in HK
Make you master or if you lost a part the same part of a other kit.
Boil a glass of water and place the Oyumaru in to a cup an pour the hot water on it, you will see that the Oyumaru will get soft, flip it around a few times so that it gets soft all over.
Take it out of the water and press your master/part into the mould make sure that everything is nice and snug too the master/part.
Set a side for a few minutes to let the Oyumaru get hard again.
pop out the master.
Then fill the mould with putty, make sure there are no trapped air bubbles, I use a mix of 70-80% Magic Sculpt and 20-30% Procreate, this gives the best of both putties, MS can be sanded and carved easily where PC gives a bit of flex.
Any putty will work, strait MS, PC or Miliput but the mix of MS and PC is best IMHO.
After a few hours the putty will be dry and can be popped out. See above for the result and below after a clean and attached to my MIAS (more about that later)
this is a lovely and easy way to make a mould and wen your done with it just place it again in hot water for a new mould. I used a bar of Oyumaru for this mould and there where 6 in the pack I bought to give you a idea how much you get.
Now the downside of the mould will not last more then a few castings most of the time and its not really useful for really detailed masters/parts.
The weapons that I made for the 15mm sci-fi soldiers there made the same way just with a 2 part mould.
so try it and if you have any questions feel free to contact me.
greetings Patrick Mondria