Check with kampfeld custom. I know he does skeleton bolt handles but have not seen the knob skeletons like your picture. Awesome guy to work with and great turnaround times have been my experience.
Not sure I'd trust a bolt that was that whittled on to survive a fall. Not worth the weight savings in my estimation. But Kampfeld is the guy to do it as mentioned.
I had a bolt handle machined similar to that and it failed and tore almost all the way off while unloading a cartridge that wasn't even a stiff case to unload. There are better ways to save .5 oz. Seriously... .5! Thats about all you'll get for a weaker bolt handle. I'll never bother with it again. Had to have a new handle tig welded on my bolt. Because of all that I have enough money into a stock rem bolt to have nearly purchased a carbon fiber stock. Learned that lesson the hard way. The cutouts were a little more aggressive on my bolt though, but still. Never again.