3D Systems Corp. shares dropped in the extended session Tuesday after the 3D-printer maker's results fell short of Wall Street expectations. 3D Systems shares fell 10% after hours, following a 4.2% decline to close the regular session at $10.59. The company reported a first-quarter loss of $24.4 million, or 22 cents a share, compared with a loss of $21 million, or 19 cents a share, in the year-ago period. The company reported an adjusted loss of 9 cents a share. Revenue declined to $152 million from $165.9 million in the year-ago quarter. Analysts surveyed by FactSet had forecast a loss of 1 cent a share on revenue of $164.7 million.