In my opinion you would be better going on an Oven Cleaning training course.
You will be shown the correct way to use the cleaning materials and the price of the course will probably include all your equipment and one months supply of cleaning materials.
More importantly, the emphasis is very much on Health and Safety, both yours and the clients as some of the cleaning chemicals you might use are potentially very hazardous.
Look back on some of the oven cleaning posts for potential courses.
To answer your question though, I don't know of any companies who manufacture the tanks but if you took plans to an engineering firm I'm sure they could make one for you. Cleaning materials vary, a look on a good industrial cleaning supplier site will give you a bit of an insight about what does what, but again, this would/should be covered on a training course.
Tom