[sbierwagen]

From the product page: http://markforged.com/ (This HN submission is blogspam)

  The incredible strength of carbon fiber comes from the 
  long, continuous strands that carry load down the entire 
  part. This is why space shuttles, rockets, and Formula 1 
  cars are constructed from continuous strand carbon.  And 
  it’s how we print.  Don’t settle for plastic with a dash of 
  chopped carbon fill. Longer is stronger.
  -
  7mm x 3mm x 100mm.  3D Printed beam is packed with tens of 
  thousands of full length, continuous carbon fiber strands

Conventional thermoplastic FDM printing has a lot of design constraints: no overhangs, voids, etc. Looking at this, it seems like it takes those design constraints, and adds some more: the fibre is aligned in the direction of the print head! This is going to take some really tricky modelling work to get it to print what you want, with the direction of strength actually oriented in the direction you want.

And how do you even cure it? Is it just carbon fibre in a thermoplastic matrix?