Two Ballnut adjuster fitting?

I am trying to save some money by making
a Backlash free Ballscrew setup with two
regular Ballnuts.
Now I need to design a adjuster fitting that
will go inbetween the two Nuts and allow then
to be adjusted to take up the backlash.
Preferably also with some spring action to
account for possible pitch errors on the screw.
May first attempts would probably work but
they are somewhat complicated and timeconsuming
to build.
Has anybody figured out something that works and
is resonably simple?
Any Ideas wellcome.