Lots of good stuff here. Nope I didn't know the touchpoint keys are doubleshot, haha.
I think molding the keys and getting them printed is pretty awesome. I have no experience in this area though. How expensive do you think it would be? I know at that one place in Washington that does custom caps, it's rather expensive for a single key. I couldn't imagine I would want to spend more than $200 to get my $20-$30 keyboard blank. I'd rather dump that into a HHKB or RF and carry it with me. But please give me an idea of the price range if you can get a ballpark.
As for manual removal, someone posted on thinkpads forum that you can do this... I'm skeptical but willing to try:
http://www.instructables.com/id/How-to-remove-Logos-from-your-PDA--cell-phone-wit/
That's surprising that the W520 has the same keyboard, haha. This link had some interesting discussion about the various FRU model numbers of the US keyboards here: http://forums.lenovo.com/t5/X-Series-ThinkPad-Laptops/Looking-for-US-keyboard-for-ThinkPad-X220/td-p/482925
Hmm, interesting. I haven't been on "parts ordering" duty in a while, so I don't know if they have the same FRU or not, but the keyboard, connector, and screw mounts are exactly identical. As far as custom moulds go, I have read that $3000 is a good estimate. If that's the case, with ten 37-key sets, you'd only be paying about $9/key. Perhaps some company with an injection moulding machine can give you a better price on custom moulds.
That said, I think sandblasting or fine sandpaper is the way to go.
Was watching Modern Marvels "Nuts" on TV the other night about how they would sandblast the space shuttle solid rocket boosters to clean them up but rather than use sand they used finely ground walnut shells, so as not to scratch them up, thought that was pretty cool. I sandblasted some engine parts way back in the day but really don't know what the blasting abrasive material was. I naively thought it must have been sand, and maybe it was but truth be told I really don't know.
Hmm, that is interesting, likely they do it because the walnuts aren't "that" hard, and won't wear through the metal, but it could also be because they will dampen the shock of impact. If you were sandblasting metal, it could have been sand (or glass: Similar properties) or Al2O3 (Alumina, or sapphire). Beth have relatively high hardness.
If you can change the sandblasting media easily, go for something softer, like walnut shells, so it'll go slower and not damage the key. Since I have almost no experience in sandblasting, all these recommendations are theoretical.
If you don't have easy access to a sandblasting setup, I'd grab some fine sandpaper and watch some movies. Others recommend finishing off with coarse paper to texturize the keycap again. I believe there was a topic about this, but I can't find it, so it must've been GHroll'd back.