A number of us have ground and polished mirror blanks in the past. My experience was over 35 years ago when I did a 4.5 inch and then a 10 inch mirror. I obtained the mirror kits from Edmund Scientific, however I do not think they have the kits at this time. You might check sites such as Cloudy Nights https://www.astromart.com/classifieds/details.asp?classified_id=146067 for an online ad from someone who is trying to sell a kit. There is a site found on a Google search that advertises mirror blank kits for a 6" mirror. http://firsthanddiscovery.com/6-inch-telescope-mirror-kit.html. However they don't include a 'polishing tool' with the kit??? (In the Edmund kit there was a second Pyrex blank that was part of the polishing tool as it was fixed to the barrel you walk around and the second blank that was to become the mirror was on top and the abrasive was in between the two. The top blank became concave and the bottom one convex. A manual described the strokes you had to make to develop the concave mirror surface into a circular and then a parabaloid surface which you could test and polish. Not sure the references above have everything you need but check it out if you haven't.