A computer-implemented method for querying a database, the database comprising 3D modeled objects that each represent a fastener, the database further comprising, for each 3D modeled object, a respective morphology signature, the method comprising: - providing a query that includes a morphology criterion, the morphologic criterion being entered by a user by inputting a symbol or by inputting a 3D modeled object that is shaped according to a symbol; - returning, as results of the query, respective 3D modeled objects of the database, a respective 3D modeled object being returned based on an extent to which the respective 3D modeled object has a morphology signature that respects the morphology criterion; - displaying the results of the query to the user; - selecting by the user a preferred result of the results of the query; - modifying by the user the preferred result in and/ or adding the preferred result to, a design of an assembly of parts; wherein the morphology signature comprises, for each respective one of a set of pairs of walls of the respective 3D modeled object, a label representative of a relative orientation between the two walls of the respective pair, a wall of the respective 3D modeled object being a pair of surface portions of the respective 3D modeled object opposite one to the other that represents a substantially regular slice-like portion of material, wherein the labels form a clique graph over the walls of the set of pairs of walls, wherein each label of the morphology signature is representative of a relative orientation between at least substantially planar walls, wherein each label of the morphology signature is representative of a relative orientation between thin walls, wherein each label is determined within a predetermined finite set of labels, wherein each wall is associated to a respective node that includes a point and a respective normal vector, the label representative of the relative orientation between a wall associated to a node ( p 1, n 1) and a wall associated to a node ( p 2, n 2) being defined according to the sign of the distance from p 2 to the plane defined by ( p 1, n 1), the sign of the distance from p 1 to the plane defined by ( p 2, n 2), the sign of the norm of the normal vectors cross product, and/or the sign of the normal vectors scalar product. - providing a query that includes a morphology criterion, the morphologic criterion being entered by a user by inputting a symbol or by inputting a 3D modeled object that is shaped according to a symbol; - returning, as results of the query, respective 3D modeled objects of the database, a respective 3D modeled object being returned based on an extent to which the respective 3D modeled object has a morphology signature that respects the morphology criterion; - displaying the results of the query to the user; - selecting by the user a preferred result of the results of the query; - modifying by the user the preferred result in and/ or adding the preferred result to, a design of an assembly of parts; wherein the morphology signature comprises, for each respective one of a set of pairs of walls of the respective 3D modeled object, a label representative of a relative orientation between the two walls of the respective pair, a wall of the respective 3D modeled object being a pair of surface portions of the respective 3D modeled object opposite one to the other that represents a substantially regular slice-like portion of material, wherein the labels form a clique graph over the walls of the set of pairs of walls, wherein each label of the morphology signature is representative of a relative orientation between at least substantially planar walls, wherein each label of the morphology signature is representative of a relative orientation between thin walls, wherein each label is determined within a predetermined finite set of labels, wherein each wall is associated to a respective node that includes a point and a respective normal vector, the label representative of the relative orientation between a wall associated to a node ( p 1, n 1) and a wall associated to a node ( p 2, n 2) being defined according to the sign of the distance from p 2 to the plane defined by ( p 1, n 1), the sign of the distance from p 1 to the plane defined by ( p 2, n 2), the sign of the norm of the normal vectors cross product, and/or the sign of the normal vectors scalar product.