the custom shape tool has this beam shape thingy, that looks like this
then while you are using the shape,
press SHIFT while you are dragging the shape to your desired size so the lines/beams are equal.
you can also use the auto select tool which is the second box in the tools section in the first picture to drag around the sunbeam thing.
for example like this
and if you want you can make it bigger by pressing
CTRL + T to enter the mode
then if you want you can press SHIFT while you are dragging for equal size
note: if you need to see the whole box thingy, like make your image appear smaller press CTRL and the - sign.