ExOne (XONE) XONE stock is down some 7% in what is becoming a bad week for 3D printer stocks.

The 3D printer company cut its outlook due to foreign sales delays. (via MarketWatch)

XONE stock dropped 15% to $52.75 on moderate volume after the company cut its 2013 revenue outlook to a range of $40 million to $42 million, from a previous outlook of $48 million, as customers in Russia, India, Mexico and France deferred purchases into 2014 because of their respective approval processes.

The bad news was reverberated to other 3D printer stocks.

Shares of 3D Systems Corp. (DDD)  fell 4.6% to $87 on moderate volume. Shares of Stratasys Ltd. (SSYS) declined 2.8% to $116. Earlier Tuesday, Stratasys gave a mixed outlook for 2014 and shares closed down 8.2%. Meanwhile, U.S. shares of Voxeljet AG (VJET) fell 8% to $38.99 on moderate volume.

As Daily Finance notes, the news could portend challenges ahead.

During its third quarter conference call, ExOne CEO Kent Rockwell acknowledged that doing business in the industrial segment is a slower and more difficult process. This is not surprising, considering the five deferred 3-D printer sales imply a price tag of over $1 million each. It’s not exactly an easy buy for a customer to make — especially without approval.

ExOne itself admits that with only limited sales each year — combined with being an emerging growth company — means that it’s concentrating on growing its service center business.

This model may in fact help with product revenues throughout the year.

ExOne sold out of its six M-Flex 3-D printers — so now plans on quadrupling production and tripling sales of the M-Flex this year.

XONE also pointed out that it was still considering its long-term organic revenue growth rate at 40% to 50%.

As with all 3D printer companies, ExOne has got its eyes on the long-term.