Polymer Clay

Has anyone used this medium before? I have used polymer clay for many years as a sculpting medium for smaller projects like stones or carvings, and for building up heels for shoes (reinforced with steel pipe and then embedded in resin with a mould), but now I want to use it in a rather large way. It's an idea that has been spooking my brain for at least ten years. When I was a Brownie, we used a mirror on the floor to represent a pond that we had to pass over, when we 'graduated' to Guides. I loved that idea (mirror for water), and what I would like to do is to embed a mirror into the moulding material in the areas where my 'painting' needs water. So far, so good. My dilemma is the size of the design, i.e. 85 x 220 cm, because the modeling medium needs a curing temperature of about 130° C. The mirrors can take the heat, that much I've figured out. Does anyone have an idea about how to cure such a large object? Or will I have to resort to an installation? If the latter is the case, does anyone have a better idea than gluing the pieces together in tiles? Or a smart way to cover the seams up? I guess I should mention that the whole thing is for a door! (The weight is also a matter of consternation.) Cheers, Holly