The present invention relates to a method for preparing a biodegradable piece for medical use including the steps of: a) preparing a mixture including glycerol and sebacic acid, b) pouring said mixture into a one-piece mould made of elastic material, c) placing the mould containing said mixture on a support, d) placing the support into a chamber with controlled temperature and vacuum level until a polymer having the desired consistency is obtained, e) removing the support from the chamber and allowing it to cool down to room temperature, and f) removing the piece thus obtained from the mould.