The present invention provides a low viscosity photocurable composition including (i) a cationically curable component comprising a polyglycidyl epoxy compound (II) a free radically active component (iii) a cationic photoinitiator (v) a free radical photoinitiator and optionally (iv) one or more optional components. The photocurable composition can be cured using rapid prototyping techniques to form clear, colorless three-dimensional articles having excellent mechanical properties.