The subject of the study is development of an articulated arm for minimally invasive heart surgery. The fixture develops as a snake-like forearm, carrying a wrist and the pertinent effectors; scalpels, scissors, sewing rigs, cameras, etc. The arm is formed by a sequence of modules having the same mechanical interface. About 25 modules have been conceived and their feasibility has been verified. A prototype of the instrument has been machined and tested. The small arm is actuated by 5 micro electric motors: the angular position of each DoF is measured by a magnetic sensor, the clamp is powered by SMA wires. An innovative control algorithm, able to cope with redundancy, has been implemented. The instrument, like a leprechaun, lives inside a box; the arm can lean out and move along the programmed path. During the surgery operation, the arm enters in the body of the patient and executes the operation. The robot co-operation will drastically modify surgery practice, giving freedom from anthropocentric bounds; the project considers such opportunities, with comments on typical control strategies and hints on actual performance, inferred by testing on virtual reality and digital mock-ups.