The ones that I make are simple and easy of you have a few tools.
I drill out the primer pocket with a 7/16" drill bit. Tap the hole with a 1/4"X20. ( Use what ever metric size is appropriate) Then with a nylon pan head screw grind down the head until it fits thru the neck. It this is a 450 or smaller I cut the case off about an 1 1/2" up from the rim.
I grind the thread end of the screw at about a 45 degree point fo ease of instalation. After it's started in the hole run it in until the complete threads are exposed.
With a sharp knife cut the point off until it's flush with the rim.

As the nylon is distorted with use simply screw it in further and trim.
This makes very good use of cases with split necks or the bright ring around the base.