Hi, d gil.

You cannot make this yourself. As far as I know, these things are not even available at retail, because they always take some know-how and figuring that professional installers have learned.

The two major companies that make this stuff can be found at www.xantech.com and www.nilesaudio.com. You can look over their sites, download instructions, call them and ask questions, and then you will have to figure out where to buy the parts.

Look for a local installer, or approach a local audio/video store to see if they will special order the items for you.

Good luck!