For this eclipse I wanted to get a bit more official than the Cardboard and tape I had used to observe and photograph the past Eclipse. So I have taken some measurements and drew out this part to make use of the ISO filter material. 

Some parts you will need

4 - #8-32 ½ " Machine Fasteners (Countersunk)

1 - 6" of Solar Filter

I had performed some post processing on the part. For one it is printed in ASA. I went ahead and sanded some of the rough edges. Also used a Dremel with a Sanding Wheel to clean out the filter inset. 

On the Outer piece, I did use a Black Spray paint enamel to help give it some more resistance to the sun and give it a cleaner look. Also I sanded the Pad that mates with the inset to avoid damage or tearing of the filter.

The O-Ring is printed with TPU (around 95A) in order to provide a gasket to secure the Filter material so it will compress in. 

Also have added an optional template for cutting the Filter Material.