Our solution for mounting altimeters and an action camera, and all associated hardware (switches, batteries, etc.) Holds up to 2 altimeters, and one action camera - GoPro or similar, up to Hero4 version (later versions with slight modification). No heavy and unnecessary all-thread. Great for the experimental payloads you've been wanting to try! Laser-Cut plywood parts glue together easily and mount in our 4" airframe tube or 3.9" coupler tube!