The ornamental design for a multi-odorant testing device, as shown and described.
FIG. 1 is a perspective view of a multi-odorant testing device, showing a first embodiment of my new design;
FIG. 2 is a front elevational view of FIG. 1;
FIG. 3 is a left-side elevational view of FIG. 1, the right-side elevational view being a mirror image thereof;
FIG. 4 is a top plan view of FIG. 1, the bottom plan view being a mirror image thereof;
FIG. 5 is a perspective view of a second embodiment thereof; and,
FIG. 6 is a front elevational view of FIG. 5.
The broken lines in the figures represent portions of the multi-odorant testing device that form no part of the claimed design, which includes the areas between the circles and rounded rectangles. The left-side elevational view, right-side elevational view, top plan view, and bottom plan view of embodiment three is identical to those of embodiment one. The rear side of each embodiment forms no part of the claimed design. The shading within the circular areas in embodiment one depict a contrast to that of the rest of the front side of the device and do form a part of the claimed design. The shading within the circular areas in embodiment three are shaded for the color gray, specifically Pantone #425U.