The basic construction of the plotter consists of a thin wooden plate (3mm) which is glued onto a thicker wooden frame to increase the stability while being not too heavy.
All the mechanic stuff is from http://openbuildspartstore.com/, it's not to expensive and even if it's IMHO not best quality it does a good job as far as I can judge. Also this saves on brain which is needed for the programming part.
The electrics consist of a teensy and SilentStepStick TMC2209 drivers. I guess I'll need the raw power of the teensy because efficient programming is out of my league.
The initial alpha firmware can be found at github.