Solely the cost the materials is about 2 USD when bought in small quantities, but I am using the least expensive clear silicone. Buying the expensive stuff (Smooth-On's Solaris for example) is about 2x-3x the cost but available in much larger quantities.
I look forward to someone cloning this, driving down the cost, and putting it on crowsupply/sparkfun or somewhere. (I mean that as praise, not malice.)
I assume decent results can be achieved with a super-cheap camera module, if the optics are a good match to the silicone part.
