A jig includes a base and one or more movable blocks. The base has an upper surface, which is configured to receive a substrate shaped as a flattened polyhedron having multiple facets. The one or more movable blocks are configured to move on the base so as to fold respective ones of the multiple facets, and to hold the substrate in a folded three-dimensional configuration.

A jig includes a base and one or more movable blocks. The base has an upper surface, which is configured to receive a substrate shaped as a flattened polyhedron having multiple facets. The one or more movable blocks are configured to move on the base so as to fold respective ones of the multiple facets, and to hold the substrate in a folded three-dimensional configuration.