I use loctite gel super glue. It sucks that it only comes in the little squeeze tubes. But it seems to work for me. I use it for overlays and elb horn nocks. Make sure both mating areas are good and flat. Use a perfectly flat sanding block or a disc sander with a table. Check with a ruler if you have to to make sure they are perfectly flat. Wipe they off clean with a damp rag, apply glue, and stick together. I start working them pretty much instantly, it takes about 30 seconds to glue.