Its a poor mans function generator, with max 5v p-p, it can generate sine,triangle, square and sawtooth wave forms http://black-electronics.com/blog/arduino-waveform-generator/
Among electronics there are two groups(IMHO) analog dudes and digital dude. I belong to digital dudes. I learned how a DAC works, which is nicely explained here http://www.pyroelectro.com/tutorials/waveform_generator/theory.html
On mechanical side
I've read this many times on the internet "Measure twice cut once". I made a mistake while drilling holes, since its for my personal use, I let it slide. But I'll definately keep a note on all cutting and drilling holes "Measure twice, cut once"