It really depends on how you want it to look and function.
Kydex is really easy to work with and can make a nice looking end product, pretty sure places on EBay ship to NZ.
If you wanted to make it quickly adjustable you can drill the stock and buy some bolts and knurled plastic knobs and do a nice job.
If you don't want to drill the stock, a stock pack or elastic ammo holder can be used to cover up and hold in position foam or wood or pieces of milk bottle to make a cheek riser.
If you don't care what it looks like then just wrap it up in insulation tape.
I made a Kydex cheek riser but decided i didnt want to drill my stock so just got a stock pack will the intention of making a foam riser to go underneath, but ended up not needing the riser as the stock pack was thick enough.
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