Add bleed to irregular shape

One thing I've done in situations like this is to make a duplicate layer, and then use the Smudge tool to extend the image a little past the edge. You pretty much work perpendicular to the edge,except where there's some linear feature, in which you extend the feature out along its length.

If you make a selection, you can got to Select - Transform Selection and adjust the selection at that point.

You can also use Select - Modify - Expand/Contract .. to expand or contract your selection

Dave

Do you mean forme cut a shape?

If so, roughly cut out the figure oversize and produce a cutter guide to the size and shape you want your finisher to make the tool to and supply it as a separate key-line layer.