Draw a Rectangle Around the Component

Select the rectangle button or use the key sequence g r.

Draw Circles over Mount Holes

Select the circle button. Draw circles inside the mounting holes. Click in the empty center of the mounting hole.

Click when the circle is roughly the hole size. Click the outer edge of the circle to manually adjust size. Select the center of the circle to move it around.

Lock in dimensions by typing d to assign a dimension constraint. You can also use the right-click menu to see this option.

Determining Distances

Whew! I know it takes a bunch of steps to get a basic jig setup. We already figured out the screw hole size and confirmed that the image matches the product page technical specs.

Now to do the fun stuff, which is:

1. Measure the distance on center between the mount holes
2. Measure the distance to each edge from each mount hole

Construction Geometry Lines

Toggle the construction geometry button. This toggles the lines from being white solid to blue dotted when drawing. These blue lines are not part of the structure, but only for labeling.

Draw a line between the two mount holes center point using the line icon or press g l.

Click on the blue dotted line between the holes and press d to see the length.

The mounting holes are spaced apart and appear to be 16mm on center. 

The mounting holes are each inset 8mm on center from the edges of the battery holder. I used the same draw line (g l) and dimensions (d) to determine this.

This sort of symmetry (16mm and 8mm) confirms that the photo alignment and dimensions are matching up with a well designed product. If you are seeing crazy values such as 7mm on one side and 9mm on the other, then you might have an alignment issue.

The last set of measurements to find is how far the mounting hole center point is from the top and bottom of the battery holder. 

After measuring using the (g l) to draw a line and (d) for dimension, it appears that it is 29 mm in either direction to the center of the mounting hole. 

Summary

With your scaled image and measurements in place, you can now jump into modeling! Turn that sketch into a solid body, create cutouts, or design a snug 3D-printed enclosure — all from a single product photo.