There is provided a method of forming a 3-dimensional structure from a hydrogel, the process comprising the steps of: (a) placing a hydrogel polymerisation solution into a reaction vessel, and (b) allowing the hydrogel polymerisation solution to react without mixing for a period of time at ambient temperature, while introducing a polymerisation modulator to the reaction solution through a reaction solution/polymerisation modulator interface, wherein over the period of time, a modulation effect gradient is established in the reaction solution, where the modulation effect has a maximal value at the reaction solution/polymerisation modulator interface and a minimal value at a point furthest away from said interface. The said method additionally includes the use of physical constraint members such as wires and/or threads.