Though the 3-D-printing industry remains a white-hot niche sector in the stock market, it's a "bubble" showing no clear path to profitability even at one of its flagship companies, Voxeljet, CNBC's Jim Cramer said Tuesday.
"Why do I mention this?" he said on "Squawk on the Street." "The 3-D printing space has been so hot that I'm just calling it a bubble. I was calling it a cult, but now I'm calling it a bubble."
(Read more: Cramer: 'There's bubbling everywhere')
Last week, Cramer identified Voxejet as one of several stocks that were part of "bubbling" across niche sectors, including organic food, cloud computing and 3-D printing. Cramer reiterated his position Tuesday.
"Three-D printers are insane," Cramer said. "Now I am going to be attacked … on Twitter because I said these stocks were expensive. But I want to say, everyone has a right to overpay. I would never get in the way of people's right to overpay.
"When Voxeljet becomes an earnings story, I am willing to listen. But right now they are the poster boy for overvalue," he added.
In contrast, Cramer cited Workday, a provider of human resources software, as a pricey stock worth buying.
"This is the most expensive stock I follow, and I think it's going to go higher," Cramer said. "Go long Workday and short Oracle, I think that's a great pair trade, as they call them in the game."
Cramer's charitable trust does not own shares in either Voxeljet, Workday or Oracle.
—By CNBC's Jeff Morganteen. Follow him on Twitter at @jmorganteen and get the latest stories from "Squawk on the Street"