Buy the cheapest one. They come to you from Amazon packed in a cardboard box. Put your rifle in the case, put that in the box, fill the voids with paper, plastic peanuts, whatever packing you have, send it off USPS Easy Peasy.
I custom cut slabs of plywood for the 2 large slab sides of the box, ship in a cheap hard case. A little more $$ in shipping, a little more peace of mind. What you have on hand or what you want to pay will determine the thickness. I think I used to use 3/8".
