Change font size of Figured Bass

[Sven Siegmund]

Hello,

I arrange songs for diatonic button accordion. The easy ones have a
simple bass accompaniment which can be played with two or four bass
buttons. To write this accompaniment easily with Lilypond, I thought
about (mis)using the figured bass notation for it. The figures of the
figured bass notation and their placement with respect to the melody
notes would state which of the bass buttons has to be pressed at which
time.

However, I'd like to change font size of the figured bass. I'd like to
have it a bit smaller, maybe not quite as small as the guitar
fingering font size. Please show me how can I do that in my minimal
example:

----------
\version "2.12.3"

melody =
  \relative c' {
    \time 4/4
    e2 e4 e g g g2
}

bassbuttons =
  \figuremode {
    <1>4 <2> <1> <2> <3> <4> <3> <4>
}

\score {
  <<
    \new FiguredBass { \bassbuttons }
    \new Voice = "one" { \melody }
  >>
  \layout { }
}
-------

Greetings,

S.