I am prone to use and abuse the things at a thrift store. Cowboy Boots have lots of extra leather for not much money... I am not a leatherworker, I am a doodler, a tinkerer, and a piddler. I am soon to try my first metal brass turning to replace a midcentury modern drawer pull. I have embroidered, quilted, etc but never any Leatherwork.
If you decide to try it yourself, wrap your knife in saran wrap, thoroughly wet the leather, place knife on a thin board, lay wet leather over it, slide it into a vacuum bag and suck the air out of the bag to mold the leather to the shape of your knife. Or so I have heard.
Those sheaths would look pretty good in ostrich. Just saying