You should NEVER use your kitchen oven for mold making or casting applications. If you don't have access to an industrial oven, you can create an alternative by building a "hot box" out of materials commonly found at Do It Yourself store or home center.
We have come up with a way to easily build an inexpensive hot box to any size you want. Our design will create convection currents and maintains constant temperatures, resulting in even heating of materials which is exactly what you need. The foam board and other materials needed to build the hot box can be found at Home Depot or other home improvement DIY stores.
View our in-depth How-To article: How To Build a Hot Box Oven For Heat Curing Materials