I did a couple of years ago. Cannot find the pictures and i've since sold the gun with case. I'll get the lad to send me on some pictures, or post them himself.

Simple as they come but effective. 12mm marine ply, cut to size. Screwed together with a support brace inside where the handle will be mounted (ffor extra strength). Made it as long as i needed, but also deeper than most other cases. Used piano hinges and a small amount of chain link to hold the lid when opened. Used a leather handle i had sitting around, and then two coats of varnish. Finished it off with four clasps.

I used foam i had around the house. Two layers of 2 inch in the bottom and another in the lid. It left an inch gap between the foam but when the rifle was placed in the case, it's 3 inches wide, it was held tightly, but not so much i could not close the lid. Just used carpet adhesive (in a spray can) to hold the foam into the case and to stick them together.

It weighed a lot but as it's only function was to protect the rifle when in transit or on the line, carrying it for long distances was not an issue.