FM synthesis. (if you don't know how that works,
check here)
You'll find best results with a sine wave modulator, play with different waveforms on your carrier oscillator (the osc being modulated by the sine wave osc) a basic square might be good. But depending on what synth you're using you may have a hefty selection. Have a play, find something that works nicely. What you're wanting to do at this point is find the sound you're after as it exists at it's most harmonically rich. In the case of this pluck sound it's what it sounds like at the very beginning of the sound. Aim for a metallic clanging drill type sound.
Play with the modulator signals amplitude, having it fairly low seems to give more metallic results as pushing it too high will move more towards a sharp saw tooth timbre and further still into noise territory.
Once you've got a nice gritty growly type sound the next thing is to make it pluck.
You can do this a number of ways but the basic process is to reduce the upper harmonics in a quick and sweeping fashion. The first thing you can do is use a low pass filter, 12 or 24 dB should do fine, a little resonance never hurts, but not too much, it's not the sound we're after here.
Set the cut off freq at 20Hz or as low as it'll go.
The trick here is to set the attack to it's quickest setting, completely pulled down if it's a fader, or turned all the way to the left if it's a knob, you don't want the filter sweeping in. Next set the sustain and release the same as the attack, and then pull the decay up to taste while hitting your key or playing a note back in your daw, play with the decay time till you start to get that pluck type sound.
The second way you can create and/or add to the pluck's presence is using the same filter settings on the amplitude of the modulator Osc in the FM process. It'll act upon the output in a similar way in terms of pulling off the harmonics, but it'll do it in a different way to squashing the harmonics out
post oscillation. Play about with both, combine them with different weightings. See what sounds best to you.
That's about it for the pluck aspect of the sound.
Now to add a bit more metallic twang to it, Comb Filtering would do really nicely here. You want the Frequency set pretty low, but not too low. Think of the frequency setting on a comb filter as the point at which it begins it's filter feedback process. Too low and you get rumble, too high and it's too sharp with not enough body, so around the low to low mids, somewhere around 200-500Hz should be about right. Play with the feedback setting. The more feedback the more it'll sound a bit like really fast delay so find a balance between this, and the 'damping' function, if your comb filter has one of course. Damping attenuates the sensitivity of feedback pickup.
Fiddle with the settings on your comb filter for a bit with these pointers as a general guideline until you refine it down to giving the pluck a little sheen, the slightly delay type feel to the comb will also give it a bit of width on the tops.
One last thing you can try to really beef it up is to run it through a granular synthesis engine (Hourglass is great for this, and free). What exactly you do here is up to you, but you don't really want to mess with the over all timing. A good thing to do is to time stretch the twang sample, up the grain length until you get some interesting phasing type effects (if done right it should add some really interesting character to the sound). Bounce that out, put it back in your daw and stretch it back down to the original length of the clean twang, then layer it over the original and balance the amplitude of both to taste.
Not all of these different processes will work too well together, the devil, as it always is, is in the detail so depending on how you do it, it might sound shit, but it might sound epic, so play about and experiment until you've got a gnarly metalic pluck. Then come back and post it up, lets see what you get
Anymore questions just ask!