The ornamental design for a swingtrainingdevice, as shown and described.
FIG. 1 is a top front perspective view of a swing training device, showing our new design;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a rear elevation view thereof;
FIG. 4 is a right-side elevation view thereof, the left-side elevation view being a mirror thereof;
FIG. 5 is a top plan view thereof;
FIG. 6 is a bottom plan view thereof; and,
FIG. 7 is a top front perspective view of the swing training device shown in use.
The dot-dash-dot (unevenly-sized) broken lines define the bounds of the claimed design and so form no part of the claimed design. The dash-dash (evenly-sized) broken lines showing the visor inserts depict environmental subject matter that forms no part of the claimed design, while the remaining dash-dash (evenly-sized) broken lines shown in the drawings depict portions of the swing training device that form no part of the claimed design.