Consumer 3D printers are an investment bubble -

Shares in outfits that flog 3D printers have fallen after a key analyst warned that they were a bubble waiting to burst.

According to Reuters, Citron Research said shares in 3D printers were vastly overvalued and that the technology has been hyped.

Recently the makers of 3D printers have turned an evolving technology used by manufacturers for over two decades toward consumers. They offer the prospect of producing everything from toys to tools in the home.

But Citron Research, run by California-based investor and notable short-seller Andrew Left, accused 3D Systems' Chief Executive Abe Reichental of exaggerating advances in 3D printing.

A report said that this had contributed to a bubble in the shares of 3D printing companies.

The report said that "appearances have become completely unhinged from reality" when it comes to the mania created in '3D Printing' stocks, and 3D Systems.

Citron said that behind every good bubble there is a good promoter and in this case we have the best in Abe Reichental.

Citron Research has made a name for itself looking at stocks it believes have been fraudulently and intentionally overvalued.

Its report pointed out that 3D Systems has made no significant advances in 3D printing technology in the past five years and that it has recently rehashed consumer products with little change.

While there is no doubt that 3D printers have a place in industry, today's consumer-level 3D printers can produce little more than egg holders, combs and plastic sex toys, Citron Research said.

However, shares of 3D Systems have tripled over the past 12 months and recently traded at more than 42 times the company's expected 12-month earnings.