This is a set of four crank sets at 4mm:1ft scale for my OO-scale model of a Southern Railway diagramme 3105 plastic-bodied luggage van. If you already have, or can make, suitable bits and pieces to model these details, then you may decide not to include this item in your order. Separate the units from the cage, and from each other, one at a time. You only need one unit if you don't break them. Taking one, clean the cut marks and locate the longest thin rod upright with its free end in the hole in the middle of vacuum cylinder, and the gently sloping thin rod furthest away from it gently against the middle of the guide marks on the chassis for the wire which goes between the brake handwheels (there are some other vertical bits of the crank unit to locate into empty spaces around the brake cylinder at the same time). Secure one or two strategic points with glue. Depending on your patience, you can attach further thin wires (e.g. brass or nickel silver, cut to length) threaded through the V loops parts you may have also attached, to replicate more of the brake linkage. It isn't worth 3D printing long thin wires.