Quote: Originally Posted by imprezive one
w00t w00t!
Just wanted to ask, are there any cheaper alternatives out there that could be used? I had no idea it was so costly.
Yes, and no, of sorts.
There is a less expensive rubber type, polyurethane RTV instead of silicone RTV rubber.
http://www.polytek.com/products/poly_mold.html
The average price is about $60 for 6 pounds, or $160 for 24 pounds.
Polyurethane RTV rubber is normally used for casting plaster or wax, but you can use it to cast plastic with the use of a release agent, otherwise the polyurethane plastic will stick to the polyurethane mold.
I chose silicone RTV for specifically for this reason, as polyurethane resin won't stick to silicone (silicone is non-stick), and you don't need a release agent.
You can still use polyurethane RTV for casting, it just takes a little additional work.
Silicone RTV is easier to use, and is more easily found at local hobby stores.
Also, all mold rubbers will deteriorate with use and time, but silicone rubbers work best for polyurethane or epoxy plastic.