A method for forming a field-effect transistor device, the method comprising: forming a fin structure comprising a layer stack comprising channel layers and non-channel layers (1022, 1006) alternating the channel layers, wherein the channel layers are of a channel material and the non-channel layers are alternatingly first non-channel layers of a first layer material and second non-channel layers of a second layer material, and the fin structure comprising a first fin part, a second fin part and a third fin part intermediate the first and second fin parts (1010s, 1010d); while masking the fin structure from a second side of the fin structure opposite a first side of the fin structure: - etching each of the first and second fin parts (1010s, 1010d) laterally from the first side such that a set of source cavities extending through the first fin part is formed in the first non-channel layers, and such that a set of drain cavities extending through the second fin part is formed in the first non-channel layers, and - subsequently, forming a source body and a drain body (1120s, 1120d), each comprising a respective common body portion along the first side and a set of prongs protruding from the respective common body portion into the source and drain cavities, respectively, and abutting the channel layers; and while masking the fin structure from the first side: - etching the third fin part laterally from the second side such that a set of gate cavities extending through the third fin part is formed in the second non-channel layers, and - subsequently, forming a gate body comprising a common gate body portion along the second side and a set of gate prongs protruding from the common gate body portion into the gate cavities. forming a fin structure comprising a layer stack comprising channel layers and non-channel layers (1022, 1006) alternating the channel layers, wherein the channel layers are of a channel material and the non-channel layers are alternatingly first non-channel layers of a first layer material and second non-channel layers of a second layer material, and the fin structure comprising a first fin part, a second fin part and a third fin part intermediate the first and second fin parts (1010s, 1010d); while masking the fin structure from a second side of the fin structure opposite a first side of the fin structure: - etching each of the first and second fin parts (1010s, 1010d) laterally from the first side such that a set of source cavities extending through the first fin part is formed in the first non-channel layers, and such that a set of drain cavities extending through the second fin part is formed in the first non-channel layers, and - subsequently, forming a source body and a drain body (1120s, 1120d), each comprising a respective common body portion along the first side and a set of prongs protruding from the respective common body portion into the source and drain cavities, respectively, and abutting the channel layers; and - etching each of the first and second fin parts (1010s, 1010d) laterally from the first side such that a set of source cavities extending through the first fin part is formed in the first non-channel layers, and such that a set of drain cavities extending through the second fin part is formed in the first non-channel layers, and - subsequently, forming a source body and a drain body (1120s, 1120d), each comprising a respective common body portion along the first side and a set of prongs protruding from the respective common body portion into the source and drain cavities, respectively, and abutting the channel layers; and while masking the fin structure from the first side: - etching the third fin part laterally from the second side such that a set of gate cavities extending through the third fin part is formed in the second non-channel layers, and - subsequently, forming a gate body comprising a common gate body portion along the second side and a set of gate prongs protruding from the common gate body portion into the gate cavities. - etching the third fin part laterally from the second side such that a set of gate cavities extending through the third fin part is formed in the second non-channel layers, and - subsequently, forming a gate body comprising a common gate body portion along the second side and a set of gate prongs protruding from the common gate body portion into the gate cavities.