The invention relates to a method for packaging molecular substances in protein shells, comprising the following steps: binding a protein shell fragment, via a first region to a matrix; bringing the protein shell fragment bound to the matrix into contact with the molecular substance, in order to bind the molecular substance to a second region of the protein shell fragment; separating the protein shell fragment with the bonded molecular substance, or the part thereof which contains the bonded molecular substance, from the matrix and assembling the separated protein shell fragments, or the part thereof which contains the bonded molecular substance, with other protein shell fragments to form a protein shell, whereby the separation and assembly can be carried out in any order.