That's interesting and looks relatively easy to make. Just need the right material.
I can speak in-depth and with great knowledge about most subjects until some bugger who actually knows what he is speaking about opens his gob .
Yes it is Kydex and not to difficult to make tho gettin it neat and tidy for sale would require a little more time and effort
I bought two kydex cheek pieces from the states for less than that , my two bolt thru the stock with adjustable knurled nuts and very quick / easy to adjust
Downside drilling into stock
But it suits me
Be damned if I can remember name of the guy who did them
I forgot to say that they also do height adjustable versions and multiple colours.