Using two rotating filter holders I made a tuned variant of the mica and polarized effect.
Each filter holder is about $6.00 so not exactly cheap, but they are well made and deliver pretty impressive results. The major downside is that they are pre-branded.
I'm definitely placing a small order, enough to make maybe 4-5 of these assemblies to then sell on Tindie. Right now I think they'll just come in a small lasercut box, nothing too fancy. Filter adapters can be used for other lens sizes, I'll have a link.
I still need to do some experimentation but I've been using a UV filter pre-stage, then the linear polarized filter, then the mica. Auto-focus was slow without the UV filter but that could be for a number or reasons and I honestly haven't logged enough time for a conclusive result. This might be because the mica filter uses "reflections" to produce its effect, this is then colorized the best I can work out and then flattened by the UV filter. Not having the UV filter might be decreasing the focus time since the sensor is looking at a reflection (or at-least a remaining component not modified by the mica plate.)
Its worth noting that right now I am using the V5 Mica (medium quality) which seems to have around a 80-85VLT (Visible light transmission) rate. The V1 is much better, but I want to cut those filters out on the laser cutter rather than by hand. I might offer an choice between the two since there is a decent price difference in the raw materials.
Now for some comparative images; they will be unfiltered then filtered:
Hopefully these give you an idea of what kind of color palettes to expect and what will be affected. This particular filter has a bias towards purple in the center of the frame, this is very obvious when you shift the target artifact off center in the window, the color will change. Blue section to the right, pink to the left of frame:
When I head into the city next I'll likely get a wider range of example photos.
I finished the packaging and included written material: