Evenin' All.

I have to replace a single block at the top of a wall.

I could buy a bag of cement and get a tiny bit out and
mix it with a bit of sand and so on, but that would be
a pain in the neck for such a small job, and it is hard
to mix accurately such small quantities. And I would
have to chop off the old mortar to make space for
the new.

Is there something in a plastic pot or tube that would
cost very little, that would do the job? Let's call it
"No More Mortar" and copyright the name, so the
next one has to be called "Sod Mortar" and so on...

BTW, the only load it will have to bear is a batton/noggin
thingy for the edge of a plasterboard ceiling.

Yours Without A Clue,
D. Pearson