Quantum devices realized in graphene and other 2D materials usually rely on etching which often leads to localized states dominating the electronic properties of the system. Here we show how a stacked gate arrangement in bilayer graphene can be used to define a constriction for current flow which can be completely pinched off and in addition displays plateau-like features in the conductance. We also show that spil-gate geometries on high-mobility MoS2 allow for the realization of an electronic constriction. These developements pave the way for electronically tunable quantum devices in 2D materials.