I didnt realise how long ago it was but after watching the video it was over ten years ago, I made a graver sharpener https://www.youtube.com/watch?v=8okY...channel=Josef1 sorry for the annoying sound!!
today I I found this on amazon
https://www.amazon.co.uk/dp/B08GP6Y8...FCTFQ62_0?th=1
and with the fine one of these
https://www.ebay.co.uk/itm/384985492...mis&media=COPY

I recon you could make a pretty cheap sharpner even better if you could secure the lap with magnetic tape. I know its not GRS but it is lots more economical !

I've not tried it as I still use the one I made, I am tempted but it may help someone out if you like a project in the meantime.