I'm certainly not the first to do this, but most are just picture tutorials. I thought it would be helpful to watch someone complete the process. Cheap circular polarization filters can be purchased online for as cheap as $5 each. The entire mod process takes about 10-15 minutes with the right tools. Easy and straight forward.
1. Take care not to damage the filter when unscrewing the retaining ring. It is easy to slip and scratch the class or coating.
2. There is a reason the Singh-Ray Vari-ND filter is over $300, but for around $10 a little color shift/drop in contrast/slight vignetting (all easily corrected in post) is worth the savings in my book.