How to create a rune for AC nwn1

I am not a scripter so I wanted some suggestions on a rune I need for my server. I want to create 3 runes all giving AC to strength builds. I want them to be un-droppable . I want one to give 5 AC , one to give 10AC and one to give 15 AC . I want to make them to give strength builds more ac above what they would get from their gear if AC was maxed out from their gear. Can I just make them on toolset and make them un-dropable or do they need scripts as well to work on my server.

You should make a script that changes the PC_Skin to have +x natural AC bonus.
Though I think it caps at +12??

I agree with the PC skin method. It is actually the creature armor slot that you equip the item to.

As for the cap, you can actually increase that in EE.

I hope this helps.