3D to physical
Blender is great for non-destructive prototyping, so we ended up with several designs in 3D space, which in the end resulted in two final designs for testing.
We had these two designs printed as a physical model via a Makerbot 3d printer. Blender can export 3d print files via the .stl option, so that was not an issue.
We bought the darkest, mattest black paint we could find to coat the printed model. This will get rid of the odd blue color of the print, and it’s easier to get rid off a black ‘rim’ during the creation and post-production of the HDRI file.
You can tweak the lensring for yourself by downloading the zip file containing the blender scene file, the .stl file and instructions PDF.
The filter ring is set up with a simple cross-section, that is revolved into full 360 geometry. It’s a simple matter of measuring the outer dimension of the fisheye lens, and the outer dimensions of the filter. Now change the cross-section for a fit.
There’s also a non-destructive way to change the amount of notches in the top part of the ring for easy placement of the filter.
When your changes are done, just export the scene to .ply or .stl for 3d printing. Use your favorite online printing service, or your 3d printer.