This is a cable puller I designed to pull a cable through 1/8" Air brake tubing or 1/8" nylon tubing. I am using .050" weed whacker line from hardware store with this servo winch to pull fingers on a mechanical hand in a remote location. The pulley is for 180 degree rotation standard servo to use cable. The spool can be used with continuous rotation servo (like Jameco 2128201) with fish line to move props or make something move. The spool should hold a pretty good length of fishing line. You will need a 6-32 tap to finish the set screw holes, also short 6-32 set screws to hold the line or cable in the pulley. The pulley and spool are made to fit right on T25 servo, might fit others if drilled. If you want to use guide bearings, they are RC Truck wheel bearings 5mx11mx4m rubber sealed bearings. 3D printed push pins hold the bearing in place. Have made about every kind of chassis I can think of for mounting the winch to something. Let me know if you can think of anything else that is needed. The spool will not fit in the protected chassis. Print the chassis with full support to hold up the upper bearing support. When I designed the spool I was thinking of a CR servo winch in a box with a 9V battery, LM7805 regulator, with an Arduino uno making spiders go up and down on fish line for Halloween props. Anyway, I thought this little winch was kind of cool. It is simple, easy to print and should have many practical uses. Enjoy!