If it is DIY, I presume the D should be interpreted to stand for design as well as do. What was your design intention?

Lets also get a batter handle on what you view as toxic. Do you means the product itself, or the proucts and byproducts that go into the total life cycle of the the product.
If it is the later case (and I am not trying to start a flame war about the merits of the Digital side) then buying a new camera every 2 years might count as more toxic.

If we are talking of some sort of coated paper to capture an image, cyanotype is not too evil. Develops in water. Ferric cyanide is similar in environmental load to many iron ores mined all the time for steel making. Ferric Ammonium Citrate is like an iron mixed with dung by products neutralized in citrus juice kind of chemical . Ferric/ferrous iron going down the drain is the same as rusty pipes.

Hope this gives you some food for thought.