Making your own filament I"m considering making my own filament, with a device like the one at http://www.thingiverse.com/thing:380987. Partly because it's another machine to build, which is cool, but also to save money on filament.

Has anyone here tried to make their own filament? My main questions are:


Is the quality comparable to typical off-the-shelf filaments? Put another way, with reasonable tuning can one produce filament that's good enough to use without a lot of frustration?
Does it require a lot of attention to tuning, monitoring, or other details (which make it less worthwhile / more time-consuming)? Warning of pitfalls to avoid is also welcome.
Are there useful things one can do this way, that are hard to achieve with off-the-shelf filaments? For example, unusual materials; better control of diameter, density, etc; or mixing one's own colors?
Quality depends on 3 things:


Quality of pellets (purity, fillers, color)
Where/how they are stored before and during the extrusion (humidity, contaminants)
Have a filter in your extruder to get rid of random junk and air bubbles ending up in your filament (250 micron wire mesh filter)



There's no secret formula the filament producing companies have, they just have very efficient and very fast filament producing machines (of course very expensive, too). But when it comes to vanilla ABS or PLA, it's almost the same content.


Personal experience: no. If you get the same pellets, store it in the same place and run your extruder in the same place, it should behave the same.
I don't think there is some filament mixture you won't be able to find anywhere, but you might be able to make it yourself cheaper. Example: mixing strontium aluminate powder for glow in the dark filament (come in many colors, not just green).


I'd recommend this design: http://www.instructables.com/id/Build-your-own-3d-printing-filament-factory-Filame/
It produces filament pretty fast (one full 1kg spoon in 3-4 hours). Just make sure you have enough experience to not electrocute yourself while assembling this as the heaters use mains power.

I personally think the commercial "hobby" extruders are not worth the money. I also own the Filastruder and it's just no different and slower than the above, unless you care about a pretty plywood case for your extruder I see no advantage and since it uses off-the-shelf parts itself why bother buying a kit like that than sourcing the parts yourself?