What materials can I use to make a mold and/or casting that are cheap and maybe found in stores?

Question

I'm wanting to find some new materials people may know about that would allow me to make a mold of an item. Also, I'm trying to figure out a good material to use for casting once I have the mold.

The only thing is I am trying not to resort to buying the usual mold-making materials, such as liquid resin, because you mostly have to buy these online and they can be pretty expensive, especially with shipping costs. I would like to find some kind of material you can buy cheaply and preferably in stores like wal-mart.

I've tried several ideas so far:

I used plaster of paris for a mold but it doesnt want to release my object, plus its crumbly.

I dissolved styrofoam in acetone to get the liquified plastic residue, but its just not working good.

I used hot melt glue to cast and with and it works great. However, i cant find a molding material to use to make the mold.

I tried hot melt glue to make the mold with, but now I cant find anything to use to cast with!

I wish that I could cast AND mold with the hot melt glue, but of course you pour hot melt glue into the mold and they would both melt together.

Heck, I've even tried using white elmers glue to cast with. It takes way too long to dry and it doesnt work.

Please, i really need new ideas to try!

Answer 1

If plaster doesn't work you either trying the wrong object (plaster is no good with a fuzzy teddy bear...) or you are not using any mold release like pam or vaseline. If your plaster is crumbly you might not be mixing it correctly. Using plaster as a mold material requires however a good understanding of mold making (read up what an undercut and a parting line is, read up on the process either in the library or the internet, there are plenty of websites). You could also use plaster bandages. Or you can use clay.

You can use plaster to cast with, you can use clay slurry (more or less requires a plaster mold). you can use wax, you can use chocolate, you can use butter, water (freeze your mold to turn it to ice. You can use concrete or you can look up paper crete for a lighter version (or mix vermiculite in).  

100% silicone caulking is also great as a mold material. Cheapest in dollar stores. Squirt it in water with a generous amount of dish washing liquid. This will make it non sticky and workable.