They're height adjustable to make it easy to level your bot and has a slot on the bottom to add a rubber band or washer of some sort to help cushion it and reduce vibrations and noise.
I'm not sure how much quieter it is, so might need thicker O-Rings on the bottoms.
The holes are tricky to get right so that the nuts and bolts fit snuggly, might need editing for your makerbot skeinforge settings.
They attach to the MakerBot by tightly squeezing and pinching onto the side panel so they're pretty easy to take on and off.
Could also design different bottoms to screw into them. I might try making something like the RepRap Anti-Vibration Feet: http://www.thingiverse.com/thing:808
You'll need to print 4 bottom pieces and 2 left and 2 right top pieces.
Press a 16mm O-Ring into the groove in the bottom piece (or better yet, use scratch guard pads like these: http://www.officedepot.com/a/products/618348/Master-Caster-Scratch-Guard-Self-Adhesive/)
Screw a 16mm M3 bolt into the bottom piece, all the way in so the head is level with the bottom side
Stick an M3 nut into the large hole in the top piece
Screw the bolt w/ bottom piece into the top piece
Slot them it into the bottom of your makerbot, make sure the square part is flush with the bottom of bot, twist the bottom pieces to adjust height