Hi. This is my modification for A4Tech KV-300H keyboard.
Pictures in gallery here with some 'how to' description text.
EDIT: a new video of the (boring) modding process.
And here a video with tesing the force on few keys with weights (read youtube description for more detailed info).

It reduces the rubber domes and results in about 9 to 18 gram actuation (press) force on keys.
Can be adjusted by cutting off more, but finally depends on the foil used inside (thickness and stiffness). And I can say this is my favourite, thinnest and lightest I found so far (well did just 3 anyway).

I've been using this keyboard since 4 months and it's been a real joy. And it has broaden my horizons for having very light pressing keys. It needs a bit of getting used to: e.g. no tactile feel, minimal travel distance (those are really benefits). And you can't just lie your fingers on it, like you would do on a regular (50gf) keyboard, but I'm always using a palm rest gel anyway.

Even if I hate long (full size) keyboards, I'm stuck to this one because of the light, nearly touch key feeling.
The keyboard itself is good quality (sure, not so good as Logitech) but keys are quite decent (just bit too square and plain), don't wobble too much, plastic is good quality (only the black board is crap). I guess they made the foil thinner to be cheaper, but this resulted in this awesome feeling after the mod.

This is my 4th such mod so far . My first (and second) were on Logitech Ultra X Flat (very decent one, just really hard, thick foil, so made it like 25-30 gf IIRC, i.e. harder to press).
My old pictures are here and final look here. It was in 2005 and 2008, I've been using it ever since, without problems. If there are any issues after such mods, they are visible/felt right after.

It's nothing fancy like my other mod with own controller and display topic here, but yeah that one is really cheap and has wobbly keys, etc. I prefer this one, but unfortunately the foil connector is right in the place which I want to always reduce (PtrScr..Pause and arrows crap section) and it's very risky to fold the foil there and then connect to it back.

If you got questions (on the level) or want more details go ahead.

I think yes.
I've looked at replies on that topic and the lightest what's mentioned was 35g.
So 18g is still 2 times less force (and less fatigue) to use.
I'm sure it'd be also much cheaper to have (instead of buying overpriced keyboards), just needs time to do it.
I usually need 1-2 days for this rubber dome cutting and gluing, is a boring task too. Certainly when doing this for the first time one has to be quite careful while doing all that (e.g. while removing key caps to not strain them too much).
Good thing about this is that this keyboard model is still available to buy, and nothing extra is needed. Just the cutters and glue. Well and a metric ton of patience OFC (e.g. while gluing).

I only have 1 job but 2 teenagers. Anyway, I bought an "ultra-light" from another geekhacker a few years ago.

As I recall, it was a Cherry MY keyboard, which has double springs, or something to that effect. He had removed one set of springs so that the force was approximately halved.

To me, it sucked, and I had bought it for the key caps anyway, so I harvested the caps and tossed the keyboard.

But a mod like that is possible on a standard, good-quality keyboard.

Everyone has their own preferences obviously, but this sounds like a way to make a keyboard nearly unusable for almost everyone.

The make force and tactile feel of the keyboard should (in general) be designed so that actuating the switch requires an intentional action, apart from just finding a key with the fingertip, but shouldn’t be stiff enough to be tiring, or to cause accidental non-presses.

Of course, if it makes you happy, do whatever kind of modification you want! It’s cool that you’re able to modify a keyboard to match your preferences.

I'm sure it'd be also much cheaper to have (instead of buying overpriced keyboards), just needs time to do it. ¶ I usually need 1-2 days for this rubber dome cutting and gluing,

Some people here may enjoy disassembling keyboards and clipping little rubber pieces for fun, but they shouldn’t be doing it for the money savings. Labor and time are expensive in comparison to mass-produced consumer goods, even nice keyboards. For someone on a really strict budget, a nice used keyboard can be had for $10 at a thrift shop or $25 shipped on ebay.

if you'll use the keyboard for say next 8 years

A cheap scissor-switch keyboard is unlikely to last 8 years of heavy typing, even in stock, unmodified condition.