The deflection of light by a gravitational field is an important prediction of general relativity. It is thus an interesting problem to illustrate the deflection by simulating the appearance of astronomical objects as seen through a gravitational field. To do this we have constructed plastic lenses to simulate the gravitational deflection of light for three cases: a point mass, a sphere of constant density, and an isothermal gas sphere. In this paper we discuss the calculation of the deflection for any distribution of mass, the shape of general simulation lenses, and the construction of plastic simulation lenses. To illustrate the results we present photos of a grid, a dark spot, and a field of stars and galaxies seen through the lenses. The photos clearly display the distortion of images, Einstein rings and arcs, and brightness intensification.