That is an item that will be better purchased than built. If you need an inert atmosphere, ehxaust fan, etc. you can buy a better one cheaper than you can make one.
I second the above post by Dtuck that it is better to purchase one than try to built it yourself.
If you will look on the surplus market you will find about anything you want in the range of curing ovens. I have been involved in several purchases of used equipment and have been quite pleased with the products. We have just bought some surplus ovens and spray booths (new) that are brand new. The price was about 1/3 the quoted price from the manufacturer.
Here is one of many out there. It is best to call any surplus site with your requirements.
