Instead of buying an adjustable camera extension arm (or Selfie Stick) for your action cam, consider if making one will work instead! Obviously this isn’t telescoping, but I don’t need a telescoping pole for my needs. Infinite adjustability is more important to me. To reinforce the endcap, glue it onto the pole. PVC adhesive would be ideal. As a finishing touch, you can paint or tape the pole so it doesn’t look like PVC.
There are other DIY camera pole mounts on Youtube. The collapsible ones usually require an old tripod to steal a leg from, and most aren’t this simple or adjustable from the camera’s point of view. I used this stick to get some creative views on my ice fishing trip to upper Minnesota’s Red lake. You can see a link to that video here: Red Lake Walleye. Extension arms are used quite extensively in action sports like snowboarding or surfing, but they are also used a tremendous amount in self filmed videos and TV shows. Tim Burnet on Solo Hunters TV uses an extension arm in quite a few of his shows while walking around on the mountains.
Just in case it isn’t obvious, this mount will work with any camera with a 1/4″-20 threaded mount. That includes GoPro, Sony, Contour, etc. While heavier cameras and camcorders will also generally mount on a 1/4″ threads, you won’t appreciate the leverage of holding that much weight at the end of a three foot pole. In addition, the swivel ball joint won’t hold up to excessive weight either. This extension arm is definitely best suited for action cams.