Relatively low strength and/or relatively low density, but ductile materials may be folded or crumpled and finely divided to give proppants for introduction into hydraulic fractures, where the folded or crumpled structure of the proppants gives relatively increased strength relative to the relatively low strength and/or relatively low density of the materials. Materials not previously considered suitable for proppants may be considered when structure or configured in this manner. Similarly to the case where crumpled paper within a cardboard box keeps it from collapsing, the folded or crumpled material spontaneously develops structural rigidity at relatively low volume fractions without a specific externally imposed design. The folded or crumpled proppants may also be used alone or together with conventional proppants for sand control in gravel packs or frac packs.