Over the last few months 3D printing companies, especially 3D Systems Corporation (NYSE:DDD), have experienced a rise in interest from the public as well as financial investors. However, recent data reveals negative trends in the 3D printing industry, with 9% of accounts receivable now past due over 90 days in tandem with a weak operating cash flow in 4Q13. Merrill Lynch analyst Wamsi Mohan is maintaining his SELL rating and lowering his price target from $65 to $60.