Top 5 Stocking Stuffers for Machinists

If you have a friend that's a machinist, and don't want to ask them what they want for the holidays because they'd say something that's several thousand dollars, there are several lower cost alternatives that would still show that you care.  Many consumables used regularly in the shop are always handy and would certainly be a welcome gift:

#5 - Lava Soap
They say machinists wash their hands before and after using the bathroom, or in my case, before only... (they're gonna get dirty again anyways).  Make sure to get the one with the red packaging since it is more abrasive and cleans better than the green packaged one (both soap bars are green and look nearly identical).  Funny that "lava" means "wash" in Spanish, yet the name comes from the volcanic pumice powder in the soap.

 #4 - #10-32 Hardware
This may be personal preference, but I can't seem to get enough bolts, washers, and nuts in this size.  The great thing about them is it is the only screw thread which is interchangeable with a metric size: M5-.8.  Additionally, these are the standard screw size on bicycles for attaching hardware, as well as 19" equipment racks for servers and music equipment.  They are a very handy size, and the socket head ones seem to be most durable.  Other size recommended would be 1/4" - 20 since it would appear to be the most commonly used one in America.

#3 - Center Drills
These are used for starting holes, and the small tips tend to break off.  Having spares of these is always welcome, especially in the smaller sizes.  For the general user, no need to buy anything larger than 3/8" diameter.

#2 - Acetone
When you really need things to be clean, few things work better than acetone.  Just don't use it near an open flame, or leave the cap open since it will vaporize, and you'll be left with an empty bottle.

#1 - Grinding Wheel Dressing Diamond
I mean hey, if you're gonna buy diamonds for your loved one, why not get the useful kind?  These are used to re dress grinding wheels to expose fresh wheel surface.  While more commonly used on surface grinders, they can be configured for use with bench grinders.

Honorable Mention: Sandpaper and Scotchbrite®
I have been caught many many times re re re re using pieces of sandpaper and Scotchbrite® far beyond when they should've been replaced.  In fact, I nicknamed myself at my old workplace "The Scotchbrite Scoundrel" since I would collect the used pieces off the floor to use at home.  These are a must for any kind of metal finishing.  100 grit is an average roughness for sandpaper, lower number means more coarse, higher more fine.