So you're car has started squeaking but when you look for the grease nipple there's just a hole with some stripped threads :(

What now?

Strip the part to pieces so you can drill to a large size and tap for a larger nipple?

No time for that? OK, I've got a solution.

Here's how I got my girlfriends beetle back on the road in record time without having to strip the whole front beam.

Safetywise, this may or may not be the best solution for you, it is merely what I did and it seemed to work very well.
You are likely going to be working under a ton of metal. Take precautions, never rely on hydraulics to support it above you, axle stands, bricks, large lumps of wood. These are the things of safety.

Step 1: Fabricate the Solution

As I said in the intro, I don't have time to strip the front end, take everything apart so I can drill and tap to a larger size, then put it all back together.
Plus if I were doing this I'd want all new bushings and bearings on standby to swap in for this poor old unloved beam.

So here's what I made.

I got a sheet of metal, thin enough to easily work but thick enough to hold a thread. It was probably just under a mil thick steel.
I drilled it before I cut it to prevent holding issues (holding small lumps of metal can be frustrating even with a vice). You guys know how to drill right? Centre punch where you want the hole, get a decent sharp bit, maybe a little cutting fluid, not too fast for steel. Hold the drill as perpendicular to the piece as you can eye (or better yet use a drill press).

Once drilled to 5.5mm, the nearest size I had to the correct tapping drill size for an M6 thread, I deburred the hole, then cut out the small rectangle of steel from the large sheet.

Bend it around a form, you might need a vice and or pliers to help, steel is tough, fingers are soft!
The form could be a broom handle, I used a mastic tube as it was close to the right diameter and just rigid enough for this thin sheet.

Tap the hole to M6. I used a first and a second tap. Didn't bother with the final as I wanted a tight thread. The sheet was thin enough I didn't worry about tapered thread shenanigans.
Make sure to tap AFTER bending, otherwise your hole will distort the threads as it bends.

Step 2: Oring

Even though the nipples nearly threaded in the old stripped holes I couldn't rely on that as a seal. I had some o-rings so put a suitable size one on the back of the nipple.

It worked a treat

Step 3: Clamp It On

Hose clips, jubilee clips, whatever you call them or the best bet here.

Step 4: Job Done

Repeat for all the required nipples, four in the case of this car.
The image shows the last and most awkward one, tricky to get to thanks to the steering box right next to it. I put the jubilee clips on the other way round for better access to tighten them.

You gotta keep pumping grease in till you see it come out the ends.
It took six refills of my (small, old) grease gun. That's about 3/4 of my pot of grease used up!

No more squeaking!

Ideally I should leave something covering the holes, 3 more of this fitting? Perhaps, perhaps I should just strip the beam and do a proper job as soon as I get time.
All I know is my girl friend is back on the road and not squeaking any more :D