This is the trim actuation mechanism on my Pietenpol Air Camper, NX41CC. No, it's not fancy and no, it's not often used. It's a braided nylon cord (deep-sea fishing line) with knots in it, a pull ring located under the pilot's seat, and a simple keyhole notch that the knotted line goes into as I pull out the trim or release it. In operation, I have set it at the desired tension to take up most of the elevator heaviness and put it in an almost-neutral condition, and haven't changed it since I installed the "system"

Here's the muscle part of the system. A bungee (Harbor Freight, less than a buck!) places a biasing tension on the upper arm of the elevator bellcrank located behind the pilot's seat, in the empennage tailcone. An elaborate system of hand-carved wooden pulley and hand-shaped bracket, Lowe's Hardware bolt/locknut, and other high-tech, modern components forms the heart of this "digital" (hey, it operates using my finger, which is a digit by definition!) elevator trim system ;o) It changes the elevator from a slightly heavy forward pressure with low fuel and no passenger and a slightly heavy rear pressure with passenger and full fuel, to even less pressure in any of those configurations. Not bad for a couple of bucks.