craftgrrl | making an ice cube tray?

okay i will try this again, hopefully the questions are understandable now, and i apologize if they are not.

i would like to make my own ice cube trays with custom shapes. i found this model making product, it gets baked after you shape it, but i assume that it is probably not food-safe by itself.

*is there anything that is food-safe that i can coat this product with to make it food-safe?
OR
*do you know of any relatively inexpensive silicon/rubber/plastic mold-making materials that would be food-safe that i could use instead of this product that i found?

thanks for your help and time :)