A cheap and easy (assuming you already have the tools) way to mount an iMac to a monitor stand.

The basic idea is super easy - drill into the existing iMac stand and bolt the vesa mount directly to the stand.

This method relies on your stand having enough of an downward angle adjustment to compensate for the angle of the iMac stand. A 15° adjustment will let the screen sit just about vertical and tilt backwards a looong way.

Tools and materials:

-iMac
-monitor stand
-marker or pencil
-centre punch and/or sharp probe
-drill

And:

-tap and die set to match bolts
-bolts to match tap and die set

or:
-drill bit large enough for your selected bolts
-bolts, nuts/nylon nut, and washers/split washers

Step 1: Mark Out the Mounting Points

Line up the mounting hardware and mark out the holes. It's a good idea to clamp it in place so it does not slide around while you are working - lining it up to the stand is not that important (most stands tilt and swivel to adjust for this anyway), but all the holes must maintain their position relative to the other holes.

Once the holes are marked out, it is a really good idea to mark the centre of each hole with a centre punch to keep the drill in place. I recommend using a probe or awl to mark the centre and then use a punch to make a more substantial divet to put the tip of the drill in.

Step 2: Drill and Tap

Follow the instructions on your tap and die set to make the threaded holes for the bolts.

This is generally follows along the lines of selecting the matching tap and drill combo for your bolt size/thread. Drill the hole where you previously marked. Taper the top of the hole with a file or grinding bit on a Dremel. Use the tap with lots of appropriate oil and slowly screw it into the hole with a turn back for every 1/2 or 1/4 turn in (go by feel - when it gets tight, reverse. If it breaks, you've turned too hard!) and cleaning out the shavings regularly.

After the tap goes all the way through and is moving freely, clean it out and test with a bolt - it should turn smoothly without needing any force.

ALTERNATIVELY...

Drill all the way through and use an appropriate nut and bolt combo to attach to the mount.

That's it! Mount it and start work on clearing away all the junk on the table.