Feedstock is the 'paper' for the print. For a standard extruder it is 3mm diameter thermoplastic round rod.
ABS is the most common feedstock. It is relatively easy to print and produces strong impact resistant parts with good surface finish (depending on how well your printer is working, of course). It has some tendency to warp, so large parts are best printed on a heated bed. When it isn't pigmentented it is a light cream off white colour. ABS is a common plastic in wide general use, and tends to be fairly cheap.
PLA is a biodegradable plastic that can be made from corn starch. It prints very well and produces parts with almost no warping at all. It is harder and more brittle than ABS. It is colourless and clear. Light shines through printed parts, but you can't see through them. PLA is less common and more expensive than ABS.
HDPE (High Density PolyEthene) is a very common plastic, but the hardest of the three to print with. It has the greatest tendency to warp. It is also soft, but quite low friction and hard wearing. It is the cheapest plastic commonly used as feedstock, so it tends to be cheap, but many people have trouble getting good results when printing with it.
|Material @ price/kg|
|RepRap Kit||from £12.99/kg||not yet||not yet|