We report on the design and implementation of innovative haptic interfaces based on magnetorheological fluids (MRFs). We developed 2D and quasi-3D MRF-based devices capable of suitably energizing fluids with a magnetic field in order to build shapes that can be directly felt and explored by hand. We obtained this effect by properly creating a distribution of a magnetic field over time and space inducing the fluid to assume a desired shape and compliance. We implemented different prototypes, synthesized and designed with the help of preliminary simulations by a 3D finite-element code. In this way, both magnetic field and shear stress profiles inside the fluid could be carefully predicted. Finally, we evaluated and experimentally assessed the performance of these devices.