A golf swing trainer comprising a set of modular cylindrical ground frame members, in the most basic form an elongated front-back member and at least two elongated fore-aft members removably mounted on the front-back member with connections that allow the position and spacing of the fore-aft members to be adjusted on the front-back members to define ground level swing/stroke paths, and one or more tilt-adjustable upright guide members removably and adjustably mounted on the ground frame members to define a swing plane. The ground frame is preferably made from cylindrical tubing, and special connectors are used that provide snap-fit, slide, and rotational connection to the ground frame members. The trainer also includes raised, angled guides that can be removably connected to the ground frame members to support a raised, elongated, horizontal putting guide at a parallel acute angle to a ground frame member. The pieces of the swing trainer can be reconfigured without tools in the field to create different configurations of right-angled ground framing and upright guides and raised horizontal guides for a wide variety of swing training exercises.