I needed a cam lock device to assist tying my canoe up to the river bank nice and tight so that it wont move when I get out and in. It can work both ways and can be locked by rotating the thumb wheel in the required direction. The device is attached to the canoe within reach. The rope is connected to one end of the canoe the other end of the canoe has the rope slide through a carabiner. After the rope/cord is thrown over a bollard or similar the loose end is located as shown in the photos and pulled tight.
Check out the mk 2 version http://www.thingiverse.com/thing:879225
Because even my basic 3D modeling skills are feeble I desgned this to be cut with a laser. Cut in 5mm acrylic which is plenty strong enough for its intended use.
Assembled with one M4 screw and two M3 screws.