http://www.ebay.co.uk/itm/Wargames-Modelling-BNIB-Mould-Instant-Plastic-Clay-/350858398918?pt=UK_Toys_Wargames_RL&hash=item51b0ca4cc6
£6.99 for 6 blocks and they can be used time and time again.
I picked some up the other day to try.
There is also a guy who sells green stuff at £6 for 12" of it (half
GW price)
The plastic clay is simple.
Drop it in a bowl of boiling water for 120 seconds.
Take it out (using a tool or anything to stop you being scolded)
Press it against the surface and let it cool down (or run cold water over it)
After 10 mins its a solid mold and can be re-used as much as you want.
Just mix up some
GS and push into it (it wont stick to it, so dont worry)
Let it set then pull it out, or do what i did and press the back against some paper so it comes away from the mould without any damage.
I have been converting jetbike warlocks and needed the chest plate runes, and within about 15-20 mins i now have 10 sets plus 5 heads.
Really is quick and easy to do.
And if you want something different, re-boil the clay and go again.
Cant recommend this stuff highly enough.
Only been using it for 2 days now but it really is amazing stuff and it replicates any small details.
My 1st test was a vampire counts vampire head, in which it copied it perfectly including eyes, fangs, eyebrows etc.
Everyone who converts even in the slightest should have this stuff