As requested here: https://teakdoor.com/photoshop-stuff/...-shop-pro.html

Step 1:

Zoom into your chosen picture by 300% or so, then select the Freehand Selection tool.



Step 2:

Use this to draw around the object that you want in colour...



... and you should be left with something like this:



Step 3:

Invert the selection (Selections > Invert).



Step 4:

(Adjust > Hue and Saturation > Colorize)



Step 5:

Set both to "0".



Step 6:

(Selections > Select None)



Step 7:

Hey presto! You're done. (But hopefully you'll have chosen a better picture than I have so that the effect stands out a little better. )