We apply a real-space renormalization-group (RG) technique to study the low-lying energy states of a strongly interacting copolymer chain on a three-dimensional simple cubic lattice. The chain is 27 beads long and consists of randomly chosen hydrophobic and polar components whereby the system favors interactions between similar beads. The RG scheme is applied by dividing the chain into different parts (conformons) and applying a variety of boundary conditions to find the embedded conformons with the lowest energy. The conformations of the low-lying energy states are found by combining the conformons of different parts of the chain. We show that the 27 beads chain folds into a 3X3X3 cube for the lowest energy state. We also obtain conformations which do not fold into a cube but have structural similarities to the lowest energy state. The model is static but can help to understand folding processes of polymeric molecules and can be extended to more complex situations.