I drilled a hole in the upper tip of my new bow for a string keeper.  I have never seen one up close, and am not sure how to rig it.  I want to avoid stretch cord if possible.  Any good ideas?

Take a piece of cord that will fit through the hole and tie a knot in it to keep it from going all the way through. Then just tie the loose end around the bowstring to keep it tight. I use the loop ends of old bowstrings, and just place it in the nock groove. Same thing without the hole, and it works great.

Here are a couple of mine. Simple. These are deer skin but a lot of things will work, even shoe stings. You can use a taut line hitch (used for tent guys) for the knot. Adjustable but won't slip unless you make it do so.

Apex,  I always used dental floss or dacron string material.  You can push it through the hole as a loop, then pull it over the tip and put the offside string through the loop and pull it tight.  Then just tie it to the string loop to keep it in place a the proper length.   When you string the bow, the thread stays attached.

Silk thread wrapped in-to the loop, then thru the hole in the tip. have string tight...on other end of the thread tie knot & add a small feather.

When the bow is unbraced the knot holds the string in place, Now when braced... You pull the feather out some and You have a wind teller....