invention is as much applicable to any other accessible lumen of the body in the decades since the first metal stent was proposed there has been rapid and copious development of innumerable different strut designs for stents for the design of stents in accordance with the present invention all of this design knowledge is available for what it is worth each material has its own characteristics and capabilities which determine what will be its mechanical characteristics and what forming techniques and possibilities are feasible clearly successful development of effective shape memory polymer stents will be facilitated by putting together in one team a person specialising in shape memory polymers and another person specialising in the design of stents as such such a team will be able to identify from the portfolio of design literature of stents hitherto predominantly metal notably stainless steel and nickel titanium shape memory alloy those designs which are of interest to the person seeking to make a stent out of shape memory polymer nevertheless a new range of design possibilities is opened up by moving from metals to polymers for example one envisages designs featuring continuous film instead of meshes with struts and interstices in this way the implants contemplated here could serve not just as a stent but also as a stent graft referring now to fig7 a stent graft 50 is installed within the colon 52 of a patient and is to be removed using a retrieval catheter system 54 the stent grant 50.