I recently designed a 6x9 version of my OSKAR Tuxedo camera, and printed it in Matterhackers Gun Metal Gray (now called Jet Grey). Only afterwards did I discover that the filament (and the resulting camera) was not longer opaque. I have received excellent customer support from Matterhackers. This is not an indictment of them in any way - They were apparently mortified that their product had changed without their knowledge. I have since received replacement spools, which I have yet to test.
However, I found myself in possession of a useless camera. So, I found a use.
I have long cautioned people to treat their 3Dprinted camera with the same respect they would afford the film inside it. I specifically caution people not to leave their camera in a car on a hot day because the melting point of PLA is lower than other thermoplastics. Today, I tested this assertion.
I donned my Schlab coat, eye protection, oven mitts and tossed the big OSKAR onto the dashboard of my Prius. The dash is dark grey, the outside temperature is in the mid-seventies (a little more than 20 degrees Celsius). In a dutiful nod to my all my chemistry teachers, at close to sea level, I effectively tested this at STP (Standard Temperature and Pressure).