Update:  If you want to find the latest on my DrawBot adventures and build log, check out this link!

Okay!  I think I’m ready to do this!  Is anyone interested in playing along at home?  Let’s give this a whirl!  Here’s what I’m thinking:

1. Type.  There are at least three distinct drawing styles among the various drawbots.  However, I suspect this is mostly a software issue.  Der Kritzler draws with lines or little cross marks.  The Polargraph draws large “square” pixels.  Harvey Moon’s Drawing Machine draws tight concentric circles.  I’m not sure I have a preference among the various methods and, really, I suspect any differences really lie in the software, not the specific hardware setup.  In any case, for a variety of reasons, explained below, I’m going to try to build a Polargraph based drawbot.
2. Documentation.  I like the Polargraph for its use of off-the-shelf parts like an Arduino and Adafruit motorshield and for its documentation.  The Make Magazine drawing machine also has a lot of documentation – but it is a very from-scratch design and there are some important images that are broken in the tutorials.  Der Kritzler also has decent documentation, but it appears to be more technical than I’m comfortable with at the moment.  One other huge benefit to the Polargraph is that Sandy Noble is still publishing updates for it – as recently as yesterday.
3. Parts.  Der Kritzler uses expensive toothed belts, the Polargraph uses (plastic) beaded cord with weights, and Harvey Moon’s drawing machine uses something with weights – probably beaded cord.  The most interesting variation for me is monofilament spool method used by the Make Magazine system.  It has a weight on the “gondola” / printhead itself and winds/unwinds filament off the spool.  The benefit for me with this system is that it won’t have unnecessary hanging and swinging weights associated with each of the two cords.  When one has kids and cats it is best to minimize attractive nuisances.
4. Sourcing.  Adafruit is out of their motor shields, so it looks like the MakerShed is going to be my best bet for picking up Polargraph-style parts.  An added bonus is that the MakerShed is located in Sebastopol, which is only a two-hour drive from my place in the SF Bay Area.  While I’m not about to drive four hours to save $15-$20 in shipping, it does mean the parts will get here quickly.
1. Arduino: $30 @ the MakerShed
2. Adafruit Motor Shield: $20 @ the MakerShed
3. Stepper motors (one for each side): $10-$38/each.  However, which should I buy?!
4. Servo motor (for pen lifts):  $15-$20.  However, which should I buy?!
5. Power supply:  There are lots!  Which should I buy?!  Will I need a second to power the steppers?
6. Since I’m planning to build a working Polargraph style robot using a monofilament spool rather than beaded cord, I’m going to forgo the beaded cord for the moment.  If I need the beaded cord, I can just print the gear/sprockets later. 1

Anyhow, your input on which steppers, servos, and power supplies is greatly appreciated.

1. Don’t you just love having your own 3D printing robot?! [↩]