I might have to try out that Amazon one. I like not having to go get a new key cut, like I'd have to do with the eBay one.
With the key portion being removable from the shell, I could easily see this shell being cast from metal. Maybe I need to look into some sort of DIY solution, I already know how to cast stuff in non-metallic materials, might as well learn metal casting
Keep in mind a metal shell would block the remote signal. You'd need a rather precise metal insert for the key blade with a radio-transparent shell (IE plastic). If you can be that precise with metal casting, DIY, I think I'll need to take some lessons from you! That'd be really neat, but I'm not sure how you'd make it happen in a DIY setting.