Create your own constitutional crisis by recording lawyer conversations in restaurants! This discrete parabolic microphone will let you pick up individual voices across a crowded room using just your smartphone. Or use it for recording bird songs. Whatever. Quickly disassembles for compact storage.
Print four quadrant pieces. I printed mine with a small brim, but you'll get less distortion of this thin-wall part if you use a fairly tall raft. Note that one corner of each quadrant is a break-away support.
Print one each of the handle, core, and nut. Print four of the tabs (optional). The handle will probably need to be printed with supports, but none of the other pieces should need supports.
Assembly & Use
The slim edge of each quadrant should slide into the grooved edge of the neighboring quadrant. Ideally, you'll get a snug fit that will hold the four quadrants together fairly securely. For added security, you can insert the little tab pieces in the holes in the perimeter to secure the rim. For permanent assembly, you could superglue the edges, or for semi-permanent assembly, you could tape the seams or else use zip ties (instead of the tabs) in the perimeter holes. Next, slide the threaded end of the core piece into the assembled reflector and then slide the handle onto the back side. Secure everything together with the nut.
The springy arms of the core piece are what hold your smartphone. It will accommodate phones from about 2" to 3" wide. If it doesn't hold your phone snugly enough, just put a rubber band around the arms and your phone for added security. The microphone on your phone will now hopefully at (or near) the focal point of the parabolic reflector.