Way back in April last year I tested a sample of PLA and got as far as making a test block with it and establishing that the warping was much less than the other plastics and you don't need a raft. I finally got round to making some objects with it last week.
The first bed material I used was balsa wood. That works well without a raft. The only downside is that when the object is peeled off it takes a few fibers from the wood with it. No big problem for functional objects, but it does spoil the aesthetic appearance a bit. The top and sides of the object are nice and shiny, but the base is cloudy.
I tried MDF, that gives a smoother finish, but I could not get it to stick reliably. Vik suggested 3M blue masking tape, but I didn't have any to hand, so I tried some sticky back plastic instead. That made objects with a nice glossy base but I could not get the outline to stick reliably.
The lid on the left was made on balsa. I think the black flecks are bits of black ABS which was the last plastic I used in the extruder. The one on the right was made on sticky black plastic. It looks much nicer, but on the top right you can see a bit of missing outline.
I also made this screw-able jewelry box, which looks nice in PLA.
PLA is very nice to extrude. It has a higher melting point than the other plastics but it viscosity falls rapidly with temperature so you can extrude it at lower temperatures. I did the first outline at 210°C, the first layer infill at 200°C and the rest of the object at 180°C. It does not seem critical.
I run the fan after the first layer to make it set quickly. I also needed a fan blowing on the heatsink of my extruder. Otherwise it can heat up past the glass transition of the PLA, which is only about 70°C. When that happens it jams fast and has to be drilled out.
Not needing a raft saves a lot of machine time and also my time removing it.
Even larger objects don't show any warping. I made this contraption to hold a scope probe in place for a job I am doing at work.
Vias are so small nowadays that attaching a wire is difficult and risks ripping the tracks off. Here it is in operation: -