Applying Mei Klaf (מי קלף) - eitzahs?

up until now i've employed a small cotton swab (q-tip) to apply mei klaf. the advantage is that a little goes a long way. i would also use the same q-tip each time, eventually causing a slightly noticeable mark to form around the area where the mei klaf had dried. i was told this was from particles of dust or dirt that had been on the q-tip.
i'm looking for a new method to apply mei klaf that conserves on the materials (and amount of mei klaf) being used
any advice?
l'chaim,
pesach

Mezuzah in "space" carved into a doorpost

If someone simply carved out a space in the doorpost and stuck the mezuzah there (inside of a case) would this be kosher? In such a case the mezuzah in it's case will stay where it is however it's rather easy to simply remove from there since it's not nailed in.

If anyone has any insights (or b'frat mareh makomos) on this please share.

scan - size sensitive

The samech of 'vesartem' is tiny. Although there is no shiyur (me'akev) of the challal of the letters, including the samech. But it is obvious that a tiny slit isn't considered at all challal, and is pasul because of shinuy tzuras ha'os.
In the case at hand, the scan shows me a samech that is pasul. But any slight variation will change the picture - the size of the challal in relation to the letter at large.

Therefore I can not decide from the scan in this case, this has to be seen in reality to decide.