Hi Aaron,
I built an eqp for my 12" dob about a year ago with alot of help from the net (don't know many people into this hobby let alone anyone with eqp build advice). I thought i'd try the "vns" design although at our latitude it'd be more appropriately dubbed "vss" i suppose
I found the calculations on reiner vogel's website (already mentioned in previous reply) very helpful for drawing up the vertical segments. I used micrsft publisher, or was it word i can't remember, to draw a circle then change its height/width using reiners formulae. I then printed actual size copies of the segments then glued them to 6mm aluminium flat bar and cut & shaped them with jigsaw and metal file. I spent a fair amount of time figuring it all out and doing it but that was basically it. I bought a stepper motor, speed controller etc online. Used a guitar slide for the vertical rollers - took the slide down to an engineering workshop to have cut and machined just a tiny bit to fit flanged 608 bearings in the ends. I designed and built a clutch mechanism for the interior of the drive roller to make it easy to return to the start position. Twist a knob to disengage the motor and it rolls freely. Not necessary - could just lift / drag it back to the start position if it isn't too heavy i suppose.
I'll link a few pics including some shots taken with a lodestar x2c camera. Although my exposures are generally 10sec or less with the lodestar, I've found 20-30 seconds is prob where image sharpness mostly seems to start its biggest decline.
I've since housed the electronics in a jaycar project box.
All the best
Nathan
http://i.imgur.com/y2Oeg6L.jpg
http://i.imgur.com/T2Hdyzi.jpg
http://i.imgur.com/8sHKgpC.jpg
http://i.imgur.com/JJcXITL.jpg
http://i.imgur.com/5q6iBNl.jpg
6 and 10 second stacked images using lodestar x2c:
http://i.imgur.com/QOhHuVZ.png
http://i.imgur.com/GBjV7IW.png