I'm working on a really great 3DP project but I will have to wait a little while before I can tell all the details. However - in this project I'm making some really cool touch-sensors with 3D printing and I thought that I'd share my experiences with the "Conductive ABS" that is sold by Reprap-Walmart (Repraper.com) and numerous others sites.
1. It's all the same
It may seem as if there are multiple vendors for conductive plastic, but in reality it's just a single, chinese company. I bought mine from Repraper.com and I suspect that most of those selling Conductive ABS are getting theirs from the same source. They all have the same spool, so it's easy to spot just this. This means that if you see Conductive ABS in a RepRap webshop, they most probably got this and all their other filament from china/reprapper.
2. It needs very tight temperature control
This plastic is difficult to print with. The main reason is that to be electrically "conductive", it contains a lot of carbon. This narrows the useful temperature area. On my printer (Ultimaker) I had to use 230-240 degrees. I suspect it will be similar for any other Reprap or other 3D printer. Anything less than this and the print delaminates (click the image above to see this on the cylinder to the right). Anything more and you also got a plug. Since I got my Ultimaker (a year++ ago) I never had a plugged extruder. While printing with this material I had 8 plugs and it's a real hassle to fix.
3. It's soft
This makes filament grinding a major issue. Took me forever to figure out exactly how much pressure to use when feeding the filament into the Bowden. Because of this, it's also next to impossible to print with retraction, so keep that in mind when modeling.
4. It's probably not too well mixed
I can't really prove this, but it seems that since most of my prints failed due to contaminations in the filament. I must have done maybe 20 attempts at printing the same model (12 cm tall & tube-like). Only one of these succeeded. This makes me suspect that some bits of this filament isn't too well mixed so that when a bit of almost pure Carbon come along, there's no way you'll manage to push that through (see #3...)
5. There's a better solution...
While it's conductive, you can't really print circuits with this material since the resistance is much too high. If you just print the same model with normal PLA or ABS and then use Conductive ink to paint it, you'll get the very same effect. No need to over-do things, is it?¨
So to sum this up - try to avoid this material unless you enjoy dismanting your printer. It is certainly conductive and small prints can probably print without a problem. Just don't think that this is as easy as other materials. It's annoyingly hard. If you know of alternate providers of 3mm conductive plastic, I'm really keen to try them out so please post a comment below.
PS: I should also mention that the color-changing filament from Reprapper.com only changes color BEFORE you put it though the printer. I got the purple-to-pink filament and after printing, it's impossible to make it purple again. Would have been fun - if it worked.