Micro-injection molding is widely used to form plastic components rapidly and precisely. Current tools for injection molding rely largely on steels for their strength and durability. The finite grain size in traditional crystalline metals means it is challenging to produce tools with features < 10 μm (Fig. 1b). However, the need for plastic components with increasingly smaller features is recognized, particularly for information storage and bio-analytical applications. For example, high volume production of millimeter to centimeter size components having features of dimensions ranging from the smallest virus (20 nm) to mammalian cells (10 μm), or the mid-section of the 'biological ruler' (Fig. 1a), could create new opportunities in the bio-analytical area.